I adopted an Akita pup almost 6yrs ago when he was 6wks old from Heart of America Humane Society. He's sleeping at the foot of my bed (on the floor) right now, as he does every night. Great dog, no problems at all.
Dogs that were abused can be fine, just like any other creature. They may need a bit more love and attention, as well as a softer touch. Just depends on what you're comfortable in dealing with. Just because they come from a pet store doesn't mean they were treated properly anyway...often times, they aren't.
As far as breeds go, do some research. What looks like a cute little pup in the store could turn out to be a 10 pound monster...hyperactive and viscious. Or a 100 lazy beast. Know what you're getting into before you do it, every breed has it's own quirks, and has it's own needs in terms of caring for them. I can't stress that enough.
If there's a certain breed you want, you can usually contact different shelters, and they will get in touch with you once they have one available. That's how I got my dog. I got in touch with someone at HAHS through emails, told her I wanted an Akita puppy, and about two months later she met me at a local Petsmart to let me pick from the litter they'd gotten in. She made me answer a lot of questions first to make sure I had the time/money/space for a dog this size, and that I was commited to owning and caring for him.
Pretty much the only requirement for most adoption agencies is that you have them spayed/neutered (if they aren't already). The dog will be cheaper ($50 is what I paid for mine), most likely have all his/her shots already, and you're most likely saving that particular pup's life.
Just make sure you have both the time and money to care for a dog of your own. Last thing a shelter dog needs is to be adopted only to be neglected, or worse, have you ship them back for any reason at all. They'll just be older, and less likely to get taken in.
