Sounds very reasonable.
A jazz trio needs to be tight, and everyone (including the bassist) has to carry their weight in terms of improvising interesting solos. If this is an issue at first, consider adding a horn or keyboard player to help fill things out.
30 tunes is a good target to get started. Eventually you want to get to the point where you can open the real book and pick tunes on the fly.
Hopefully you're doing it for fun and not for money

Figure $50-150 total for a coffee house gig if you're lucky. And maybe some coffee if you're really lucky
Cheers,
Jeff