Their EDGE speed is the same as AT&T. They use pretty much the same towers!
Cheapest data plan on t-mo - $5.99, and that is Unlimited EDGE with the only caveat being that it goes through a proxy, $19.99 for all of T-mobile hotspots and their real EDGE
And the lines really are up to you, do you want Myfaves? Unlimited weekends/nights?
The cheapest plan has free weekends and 300 whenever minutes at $29.99
For $39.99 you can get 1000 minutes and unlimited nights added,
OR you can get MyFaves and 300 anytime minutes and unlimited nights added. MyFaves lets you call any 5 numbers you want unlimited for free anytime you want.
Don't know about 2nd lines, but I think they are $10 extra per month per line. But don't quote me on that.