I LOVE cats. I have only had two, the two I have right now, Neko and Willie, but I have been volunteering at cat shelters for about two years so I've met quite a few. Nobody in my family liked cats, some of them downright disliked them, I was indifferent, meh they're okay. Then we got Neko and everyone fell in love. My dad was the biggest suprise, he really didn't think he'd like cats (only cat he ever had liked to urinate on HIS clothes) but now adores them. I really like to talk cat (so sorry for the long post lol)
As far as temperaments go, you can really get everything. You can get a cat who is much happier doing his own thing than having anything to do with you, or you can find cats who are attention whores that want nothing more than to be all over you and follow you from room to room. Some run and hide when strangers come over, some run to greet them. Both of my cats greet me at the door. NO they don't run up and rub, they just run over to see that it's us and then commence with normal activities. Like with dogs a kitten's personality may not tell a lot about their adult personality. I definately enjoy cats as much as dogs, but they fill a different niche. You can't take them out and about of course (well for certain cats you can but usually not), structured games and training don't usually happen. So in that way they are certaintly no replacement for a dog, but they are certaintly just as good IMO.
I do like kittens though, I actually have a mild fear of adult cats (doesn't make me like them any less). At the shelter I am always very nervous of picking up an adult or touching one in the wrong place, they don't give too much of a warning when you've done soemthing wrong. However once I get to know the cat I learn which cats are cool with handling and which ones are not I am pretty comfortable with both groups. It's not important he like handling but that I know how to handle and read each cat. There have certaintly been cats at the shelter though that I know would be fine with handling once they gained my full trust and were out of that stressful shelter environment. Because I worked with both my cats as kittens they are absolutely fine with nail clipping and me touching them everywhere. You also learn to read your cat very well, each cat communicates differently, with different body language and vocalizations.
As far as general care is concerned they are pretty easy. Nail clipping when the nails start getting pointy. I usually know it's time because they start using their scratching posts more than usual and you can see and feel that they are sharper to the touch or when one of them is pawing at your face. You should do something for their teeth. What you do it up to you. Brushing and raw are the best, a totally raw diet being the better of the two (and not pre-made or ground). There are also things you can add to water, enzymatic gels, all sorts of things. It's up to you. Brushing depends on your cat's coat, my cats need no brushing, I do it when they shed heavily (like twice a year) and did it when they were kittens so they got used to it.
They need a litter box. One for one cat is fine unless your house is gigantic. Keep it clean, no cat wants to walk in a nasty litter box, they rather squat down beside it. I've never had trouble litter "training" my cats. You just keep them in a small room for the first couple of weeks with their litter box, food and water, scratching post, somewhere to sleep, and some toys. Make sure there is nothing like small area rugs on the floor and they will quickly choose the litter box to go in.
The cat will most certainly try and use furniture to scratch. I have not had any problems getting mine to learn to use the posts though. The most important and sometimes the hardest thing to do is make sure you find a post they like. If they don't like it, they are not going to use it, and they have a deep urge to scratch so they will find something they like. If you get one of the carpeted ones make sure it is TALL. Most ones you find are far to short. The cat should be able to fully stretch up when he scratches and the post should be sturdy, if it tips while they use it they are unlikely to go back. Some cats like vertical and some horizontal. If you have a cat who likes the flat cardboard ones then those are great, Neko likes those. For willie I had to make a post out of a flat piece of wodd and some fabric remnants. He didn't like cardboard or sisal and I couldn't find any carpet ones big enough (I have a cat tree made of carpet in my room but it's best if the post they use is close to the furniture they scratch). Once you find a post the cat likes you can encourage more scratching by putting catnip on it and rewarding the cat as soon as he finishes using it (I don't suggest rewarding while they are scratching as they don't get to finish). If you catch them scratching stop them (I generally take both front arms and remove them) then pick up the cat and take him to his post. Do something to entice him to scratch the post like drag a toy across it. You can also deter them from scratching furniture by spraying a citrus air freshener directly on the area they scratch (might not work for every cat though) or putting double sided tape where their paws hit when they scratch. When we get new furniture I put hand towels on the arms so that they won't scratch them (they do not understand that the no scratching rules apply to new furniture, it doesn't not generalize well) until they get used to the furniture being there and then take the towels off only when I can watcht them and be able to redirect them.
Every cat likes different toys. Most like the really cheap ones you can buy that are like little mice or crinkly balls. Some like balls of paper and ping pong balls. Some like the toys that are on a string and stick. Make sure the toys will hold up to rough play, not all toys are made well. If you buy a toy with a bell cut it off or only allow supervised play. I never leave my toys on a string out since I found one of them half way down Neko's throat. The favorites at my house are "Da Bird" and the "cat charmer" (which is the one Neko swallowed). They also just like the little toy mice, those are actually the ultimate favorite.
And now my favorite subject: Food.
Cats main diet should be wet food or raw food. Dry should either not be given or be given in small amounts. Yes, dry food contains the nutrients necassary for them to live but it is delivered in an inappropriate form (dehydrated food) with lots of carbs (which leads to obesity and diabetes). Even grain free dry foods MUST use a decent amount of carbs in order for the food to pop out of the extruder in a dry, hard kibble. Wet food does not need to do this. You'll notice that a cat does not drink as much as a dog. You can play with them super hard and they won't go get a drink afterwards. They have a very low thirst drive because, as desert animals, they are designed to get most water from their food. So most cats fed mostly dry food are in a mild, chronic state of dehydration. This can lead to very concentrated urine which can lead to the formation of crystals which can lead to UTI's and stones. Some people may disagree as plenty of cats do "fine" (though I think most cats are overweight, my vet seemed oddly estatic that Willie wasn't) on mostly or even all dry food, but to me it's not a risk worth taking.
A great book on nutrition (it has some other stuff but is mainly nutrition) is called "Your Cat: Simple New Secrets to a Longer, Stronger Life" by Elizabeth Hodgkins.
I would definately go for a shelter cat. If you are picky (as I am) try and find one in a foster home or find some way to spend a lot of time with the cats, maybe volunteer at a cat shelter, as a volunteer I get a really good handle on the temperaments of our cats. Cats don't always show well with strangers, especially in the shelter, so the more time you can spend with the cats there, the better. You can easily find both cats and kittens in the shelter, NO problem. You can find some purebreds, mainly Maine Coons and Siamese (or ones who are obvious mixes of those). Or mixes that come in all the shapes, colors, and sizes you can imagine.
Kittens are going to be naughty, they will scratch the furniture, scratch you, try to climb the curtains, go in and on things you don't want them to, and act like complete spazzes sometimes. They will try to attack your feet and anything else that moves (like you under the covers). I still think they are easier than puppies though, by a lot. If you'd like to avoid most of that or you'd just prefer an adult for any reason you will have no problem finding a good adult cat. When you bring him home you might have to deal with some initial fear but unless you choose a cat known to be shy he should warm up quickly enough.
Some resources:
Forum:
Cat Forum : Cat Discussion Forums
Nurition:
(I do not agree with the methods of feeding raw that some of these websites promote, I do not like grinding which then requires supplements unless you really have to):
Feline Nutrition
Feeding Your Cat: Know The Basis of Feline Nutrition (make sure to go to the obesity section and check out the case studies, they are shocking)
Raw Fed Cats (if you are interested in raw this is how I suggest you do it)
Lots of stuff:
(I have not read every article so it's possible there is some outlandish stuff, but I've read lots of them and they seem good)
Little Big Cat
Hope this is what you are looking for, sorry it's so long lol. If you ever want more info I'd be more than happy to help