My terminally ill father is financially dependent on me. How can I protect myself and recoup expenses when he passes?

I (28F) am financially supporting my father (59M, in PA) who has end-stage liver disease due to severe alcoholism. He’s a veteran (9 years Marines, pre-9/11), self-employed but not working, and lives below the poverty line. From what I’ve gathered, he has no savings and has substantial debt (taxes, mortgage, credit card, medical, etc.). He receives some VA disability benefits and has decent equity in his home. 

I am currently covering his mortgage, cc, and other bills while he is receiving treatment, as I have done all of the times he has gone to rehab the past few years. He’s deeply ashamed of needing my help, but I have given him ~$20K total over the years. I’m his only child, and I haven’t co-signed anything. I am not his POA. 

I don’t expect any inheritance, but I’m concerned about being left to manage everything, including a funeral I can’t afford and no claim to any reimbursement. I’m way over my head and am meeting with an accountant and attorney soon but want to be as informed as possible. At this point, his cognitive functions are declining too, and I realize I need to change my approach and act quickly. 

Some questions

• Am I legally responsible for any of his debts? Would creditors come after me after his death
• Should we keep paying anything beyond the mortgage?
• Can I formalize past/future financial support (loan, lien, etc.) so I can claim it before other creditors?
• Should I ask for equity/ownership in the house (~$100K value) to offset my contributions?
• Should he have a will or any other directives?
• Should I become POA? What would being the executor entail with such debt?
• Should we consider selling the house now?
• Are there VA/veteran benefits that might help either of us?
• Any other strategies or things I should consider now?

Thank you!!!