Its better to get it form breeders if you're planning to keep them as pets as their health and life-spends and intelligence usually has a little difference.

Their life spend is from 2 years to 7 years. There are some over sea forums that said most of fancy rats now live up to 9 years.

Read my blog to know more about rats..
http://schoolofrats.blogspot.com

I'll to ask to ask around k.. how many are u planning of taking? What grade do you wan??

Basically there are 2 types. One are breed for feeding purposes, and another are breed for keeping purposes. Basically they are the same, but just because normally feeder rats are inbred, and also due to the fact that most feeder rats aren't given good care,  so they might suffer bad health or have other complications.

Both also can keep wan. I'll help you take a look around if there is any.

Both also can be tamed wan. Yes, you can train them to poo poo and pee pee only. Actually they will naturally do that, but don't expect they do it for the first one or two times. Besides, you'll also need to train them for not biting your stuff at home though time, or you can choice to bite prove your room or the play area. Rome was not built in one day. So you'll surely need to give a lot of your time and patients to educate them. It'll be a lot more easier if you get them since they are babies.