If you want simple numbers, 80-20, capital by LP vs. capital from GP, GP will usually invest first 10% before raising any funds (legal, deposits, maybe plans, etc.)The return will be pari passu on contributed funds first, thereafter say a 50-50 return.

You are pretty much on the money there but when you say a friend renting from you do you mean renting that house and you not occupying the home? 

I have to many irons in the fire I guess you could say.  As

@Ramon E Alvarez I want to say I heard that a charge on your credit card to, say, a used tire store is a ding on your credit profile.

Impossible to say as no such law currently exists....and is unlikely to exist anyways.

Have them say a number and a date they can be out by.

A really basic method is to just jump on Zillow, choose an area/neighborhood, take note of the average price to rent say a 2-3 bedroom house, or whatever your criteria are.

Let's say a triplex costs $300k where you are and each unit can rent for $900.

@Maritza McKinneyI wouldnt say a word to her unless its affecting other units.

Needless to say, a duplex.