Probably not. You could prove that your father did not have the capacity to tranfer the property in a suit to quiet title. Sounds like a long shot....

Probably not illegal. If a price is struck, how will you hold the girlfriend to the agreement? You need an attorney.

IF your title is clear then if the criteria is met for the bank then there should be no reason you cannot get a home equity loan.

Your mother could sue the estate. Probably out of luck. See legal concept called laches. Also, the insurance policy is not part of father's...

Yes, if it is your name on the title you can sell and transfer the property.

If your grandfather is competent, then he can revoke his poa at any time. If not, you will need to obtain a guardianship. If appropriate you might...

Get POA from husband. Demand return of vehicle. Call police. If husband is still competent, hurry up and get POAs and an estate plan done.

If he is not competent, then Grandparent cannot legally sign a POA. Perhaps you can obtain a guardianship over grandparent. See an attorney in CA.

If you do not have an interest in the house and a child of grandparents does, then you are out of luck. Start looking for somewhere else to live.

You may need to probate more than one estate to sort out the title. The good news is that if someone is appointed over the homeowner (s') estate...