Can I redact bank account numbers when applying for a Non-O visa and what are the re-entry rules on this visa?

You can redact them as long as your name is there BUT if they need the copies with the account number they'll send you a request for more documentation. Some consulates are okay with you doing it and some are not

As far as once you get a 90 day Non-O visa, it's a single entry, you're stamped in for 90 days, if you need to leave/come back during that 90 days you'd buy a re-entry permit either at the immigration office where you live or at the airport when you fly out.

You can do it as much as you want (single re-entry is 1000baht multiple re-entry is 3800baht)

Remember though having a re-entry permit doesn't add time to your existing stamp, when you come back in you'd get stamped until the expiration of the original 90 day entry stamp