I can't think of any online resources off the top of my head right now (used to have a few bookmarked until my computer crashed), but my biggest advice to any prospective puppy owner is to enjoy them. I know I freaked out a little (ok, maybe a lot) wanting to do everything exactly right that I nearly forgot to just enjoy puppyhood (especially with Dance, but I almost did it again with Ripley) while it lasts. You're going to make mistakes, but puppies are very resilient, so don't be constantly afraid of ruining him/her because chances are you won't. I think my hugest resource that I learned far more from than a lot of books or websites can tell me was my breeder and other fellow dog people.
I don't think there is such a thing as too much socialization. Kind of like with training, if the puppy looks mentally exhausted, I'd say it's time for a break. But overall I think it's pretty difficult to over socialize a puppy. I can't remember when the fear periods are, but I think one happens between 8-12 weeks and the other somewhere between 6 and 12 months. Some dogs seem to have another fear period after a year old, too. Things to watch out for include the puppy being more cautious than usual. To be honest, my dogs never went through a major fear period, but I noticed a little less confidence around certain things. And Ripley went through a period between 5 and 10 months where he'd scream if another dog he didn't know wanted to play with him. Just try to make sure all social interactions and experiences are positive and you should be fine. I started exposing my puppies to anything and everything possible as early as I could. Thankfully the Dobermans' breeder has a super busy household and so even before they came home they experienced a ton, but after I got them around 9 weeks or so, I exposed them to as much as possible pretty much right away I thinl (except for strange dogs until they were closer to about 12 weeks I think). Dance I didn't get at quite as young an age and her breeder didn't have a chance to get her used to a lot of things either, so socializing her was a much bigger challenge. But I took her as many places as possible pretty much as soon as I got her also.
As far as exercise, no hard core fetch or running on pavement or anything for a little while, but I found my guys were fine with off leash exercise or playing with other dogs and would stop on their own or slow down when they had enough. Short (15min) leash walks were good too until they got older and could handle more.
It's been a few years since I've had a puppy, and it's amazing all of the things already that I seem to have forgotten! It comes back quickly once I actually have a puppy, but to sit here and think about how I actually raised them is harder than I would have thought. They're so easy now compared to then, haha.