You could also look at lease options and fix and flip with a joint venture partner.

Where can I find a contract for JV ,joint ventures for Texas?

It depends how this person's estate was set up, my suspicion is you don't need to involve the son if they were both his parents as their joint ownership of the house would go to the other if one passed. 

Every tenant should sign the same lease agreement and it should include a "joint and several liability" clause that essentially says each individual is 100% responsible for the terms of the lease.Cosigners should sign a different agreement because they are financially responsible but don't occupy the rental so some clauses don't apply.

I think you could jointly apply, but check with your lender. 

I am actually currently in the process of obtaining a variance to convert my own property which is in a RSA-5 district into a two family dwelling. to start: the current zoning board is very developer friendly, so you have that on your side. the other factor that you have on your side is a genuine hardship.

I suggest you verify all information you get on public forums like BP that could be financially costly.Money an owner makes on the sale of his or her principal residence is excluded from being taxed up to $250,000 in gain for a single person and $500,000 for married couples filing taxes jointly. 

You seem genuinely interested in being an awesome PM.Something I've always sought and haven't seen a PM offer yet is stretching the vacancy-fill fee  out over the tenancy. 

and most of all, be genuine.  

We were married for 30 years, and during that time the rent checks were deposited into our joint checking account which provided the funds used to pay mortgage, property tax, and other expenses such as HOA.