Bell training

I've finally decided to bite the bullet and teach Abrams to jingle bells hanging by the door when he wants to come in from outside. Although I may or may not have bells inside for him to jingle when he wants out, I need him to offer another behavior to tell me he wants in from outside besides throwing the entire weight of his body at the storm door or, if he isn't given access to the door, barking. Jingling bells seems to be a better alternative and won't tear up my door, or annoy the neighbors when I'm in the middle of something and he needs to hold his horses.

I just have two questions:

If anyone has any practical experience, what is the best kind of bells to purchase? I really don't want anything loud or annoying, and inexpensive is a must. (I did have a momentary thought to teach him to paw at one of those desk bells that you ding for service, and just keep that out by the door. LOL But I bet that would get annoying rather quickly.)
The bells will be outside on the porch, and if the wind gusts just right, they will get wet, if that matters. Rusty bells may not be the best thing.

Also, am I right in saying that teaching him to ring the bells is as simple as having him nose or paw the bells, then opening the door for him? I'm assuming he'll catch on fairly quickly, but if there was a specific training technique, I'd love to know!

With our guys we just hung the bells on the door. It rang every time we opened the door so there was a Pavlovian response built into that... bells ring, door opens! That was built on by whenever they were by the door exploring and would "ring" the bell (just by manner of sniffing at it or running into it), we jumped up and opened the door. The connection of "Oh, so I can make this happen on my own??" just kinda happened.

BUT with Georgie and Payton, it was a question of they didn't have any real signal to notice. Payton would go to the door and just stand there looking at me. I would shortly notice he was actually standing still and realize he needed to go out. Georgie would go to the door and circle around a few times, and my mom would be in another room totally out of view of the door and with the TV up loud, so she wouldn't notice, and Georgie would then pee on the floor.

Auggie, however, already had a habit of barking and throwing himself bodily at the door. He HAS learned about the bells, but he is also a persistent little bugger and his "ringing" is sometimes still bodily throwing himself at the bells, and if I don't get there RIGHT THEN (like if I'm, you know, peeing in the bathroom or something) he will bark and throw himself at the bells again, and repeat until I manage to get there and let him out.

So it won't necessarily solve your problem of him throwing himself at the door and/or barking. It does provide another option and provide the correct desired behaviour, but that in and of itself doesn't always 100% extinguish the undesirable behaviour.
We also have a barking-and-jumping-on-the-door-to-come-in issue and as of yet I haven't been able to solve it except to try and let them in before the complaining starts. I try to wait until they are quiet and not jumping before I go to the door and open it, but it just hasn't been successful yet. Pepper is the worst because for so many years she was just plain allowed to jump on the door at her old house. She then taught Payton to do it. =P The idea of bells outside is an interesting one. It will probably frighten Pepper (she still won't ring them to go outside.)

I'm hoping that if I ignore him body slamming/barking to come inside and only let him in after he rings the bell, I can wean down/eliminate those behaviors. The brat will body slam the door, then do a sit/stay because he knows I won't let him in until he's sitting calmly. He just slams into the door to say, "HEY, I'm done pooping, I'm out here sitting nicely, HERE I AM." Barking is his last resort, and he only does it when he physically can't reach the door to body slam it. (I found that out when I moved his chain back so he couldn't reach the door to prevent him from slamming into it...) So if I give him access to the door, but have him ring the bell in lieu of body slamming...I would be much happier.

He doesn't really have a signal for when he needs out besides going and standing by the door, but since he's only allowed in the one room (of my two room apartment), he's fairly easy to notice when he's waiting by the door, so its never been an issue (unless Mike was watching him and was engrossed in a video game - but I don't think bells would have helped them, either LOL).