Ask to speak to a supervisor and work your way up the chain.

Unless the lease separates out individual rights and liabilities how you split the rent is of no consequence to the LL. Typically all signing...

There is none unless the lease allow the LL to early term. Otherwise you will have to consider buying the tenant out.

You can always make such an argument. Depends on whether they agree.

You will need to retain a lawyer to address these issues. Use the find a lawyer feature for that.

Yes. Tenants are subject to the landlords right to stay. If the LL is evicted - so go the tenants.

This cannot be answered in a blurb. You will need to retain a lawyer to address this issue if you can't get it resolved.

A few weeks or so likely at best. Better play is to get out BEFORE any eviction lawsuit is filed as the eviction filing alone will make future...

Sure - and he presumably could change them again and lock you out. This needs to be resolved not perpetuated.

No. That's patently absurd - you have to provide access at some point but not leave the place unsecured.