What can I do if landlord refuses to give key?

You seem ambivalent about what you want. If you can't get the money, then you want to move in. That must mean the noise isn't too bad. Jack

The Statute of Limitations "clock" generally starts when the claim first arises, unless it is either impossible or impractical to know that the...

Plenty, depending upon how far you want to go in order to resolve it. Jack

Not sure. Did you ask for a reason? Jack

With a court order or a settlement agreement. Jack

Should I renew or not?

A good question without an easy answer. First consideration: can you negotiate rental arrears forgiveness? Second: what effect on rent due to...

Selected as the best answer

At what point in the house closing process, can I walk away?

More information is needed. Different scenarios garner different answers. Jack

When? The answer may or may not depend upon the amount of time that has passed.

Yes. NYC Noise Code and other private rights of action. Jack

The short answer is that a roommate does not have tenancy rights. Jack