When I purchased my iPhone I was able to get unlimited data for 30 a month. AT&T changed that though so now you get I believe 200 MBs for 15/ 2gbs for 25 a month. A rip off if you ask me. Don't forget to factor in texting packages and voice.
Really, you're better off going with the Sprint HTC EVO. It's basically the Incredible but with a larger screen and Sprint has much better plan prices. It's also pretty competitive with the iPhone 4.
Now Rosa and I share a family plan but I'll break it down for you:
135 a month or so.
450 shared minutes, unlimited nights and weekends, nationwide long distance, free calling mobile to mobile with other AT&T users. Rollover included.
Unlimited data for just myself. It would be either another 15 or 20 for her to get data.
Unlimited text messaging for both.
I had a customer call in and I have yet to verify this but he claims has 2x EVOs with the Sprint family plan. Him and his wife pay 120 a month for unlimited data, text, evenings and weekends and I believe he said unlimited any time minutes but that sound's too good to be true.
As for a bank, I'd recommend Bank of America. I've also heard decent things about Chase. They're the ones who financed our car but our experience with them is limited.