Cell phone questions.

[shilala]

I have AT&T, Lisa and I run iphones. When we went to florida recently, I fell in the ocean with our iphones (and my camera) and had to get new.
When I did, it was cheaper to get two new lines to replace the phones. With the new lines I got two new sim cards and haven't used them.
Lisa would like to get rid of Vonage and her crappy router, so I'd like to pick up a phone, pop the sim card in it, and she can use one of those lines for her house phone.
The questions are these...
1.) What kind of phone do I need to get? Can I grab something on ebay?
2.) Will I just stick the sim card in and it'll work, or do I have to do some sort of activation process like Verizon?
3.) Can we port her Vonage number over being as we already have the sim cards and they have their own numbers? Neither one has been used yet. Strike that, they may have been in the new phones when we got them, but only for seconds. We haven't used them since, and didn't use them at the store, but the girl there may have.
Thanks, guys!!!