You would have a tough time arguing the one bedroom vs studio point since it should have been obvious that it was a studio when you (presumably) viewed the property before putting an offer in. Any argument on false advertising regarding that point would be pretty flimsy. The tax issue, though, might be another story. Being a positive person, my gues is that the seller made a mistake with the tax abatement issue and didn't intentionally mislead you. That might not be the case. Proving that a seller TRIED to mislead can be tricky.

I will echo the other posts in telling you that your best bet is to seek the advice of an attorney.

You are probably just fine. You are experiencing the dreaded "Buyers Remorse". If you trust your agent and you were happy with the deal when you made it, then don't try to second guess yourself. Just enjoy your new home.