You can... It is a small claim you can file by yourself, but you need a mechanics testimony that there was negligence.

You can try to sign under the LLC, but the landlord will probably have you personally guarantee.

You do not need a notary. You need 2 witnesses.

Anybody can sue for anything. The issues is whether you have a reasonable chance to win. In a slip and fall you have to prove the negligence of...

The date is of no importance. A new PoA will supercede the old one. This time, keep a copy. Probably need an attorney.

If your name was not on the Deed you have an interest though Probate. Open an estate or get an attorney to.

If the signed lease has a date to submit the security deposit and it has been breached, move on.

If there is a written warranty, read it carefully. then act accordingly.

A new act can be grounds to file a new action.

It is your duty to take care of the property. Insurance is a necessity. But it may be wise to discuss with the heirs.