What's the oldest iPad that still supports GarageBand?

I'm considering purchasing an iPad 2 or 3. Basically the only reason I'm thinking of purchasing one is for GarageBand. I'm willing to wait until I find a reasonably priced iPad that is newer if I knew for certain that Apple would still be supporting it with updates for a few years. My question basically is

1. What's the oldest iPad generation that still supports Garageband?

2. Is GarageBand on the iPad even worth the time for somebody serious about making high quality recordings?

3. From experience, what is the best iPad, if any of them, for recording with GarageBand?