Typical Morris/Oceanpoint situation it appears. 

You typically don't have the opportunity to inspect them prior to purchase, the occupants may not leave, the occupants may trash the place and steal doors, appliances, and cabinets on their way out, or you may discover it's so damaged it needs to be torn down.

Those typically yield the highest conversion rates.

I know there is generally a better rate to be had when putting down 25% vs 20% but what is typical on higher down payments, say between 25% and 50%?

Typical returns are 9-12% plus points if you charge them.

3) how much do you typically get per room?

You can typically only get a HELOC for 70-80% of the equity you have in the house. 

But what's the typical  yearly income / cost of house cash buyers are looking for without factoring expenses

Just wasn’t sure how long this typically takes.  

I would typically recommend a partnership (2 person LLC) that files a separate form 1065 for tax purposes.