What is the process regarding probate/estate when a person passes away?

My dad is very ill. He has had a very short but difficult battle with a rare and aggressive cancer, and is expected to pass soon. He has no will/living will. The only debt is a mortgage where he is the sole mortgagee and there is a paid-off vehicle that is also only in his name.

There are two bank accounts, both of which I am a joint account owner.

My sister and I are equal 50/50 beneficiaries of his retirement plan.

The beneficiary of his life insurance policy through his employer is in my late step mother's name and according to that company, it will be split between my sister and I since she is no longer living.

Can anyone point me in the direction of finding out what happens after he does pass? The said house still has a mortgage balance of over $55k and my dad wants it to "go back to the bank". Aka no one in the family wants it or is in any position to move in, become a landlord, etc. In that situation, does the bank take charge and try to sell it or what?