Traditionally a percentage of the raise is paid to the person who raises the cash. 

Looking at it the same way as a stock in terms of the percentages in a portfolio minimizes the stark difference between real estate and equities and puts in perspective as another investment one way or another. 

I am assuming that since you are giving them a preferred return, that you are getting the larger percentage?

Additionally, for multi-family deals, investors typically get a share of excess cash flow or equity on resale based on their "percentage interests".

Evaluating a mobile is different than a single family home in that some of your percentages of cost to repair will be different...most of my experience is in the midwest where mobile homes cost in 1k-40k range. 

If you plan to have this as an investement only property and you live at another location, you could have your Roth IRA buy the property, or a percentage.

You could be underpaying or overpaying and there’s no way to know with percentage metrics.

All partners contributing equitable cash.1st property was almost turnkey - took a little paint and spit n polish and it was up and running.2nd property was a total rehab, then converted to rental.The way we decided to do it is that on the first property, the partner who is managing that property gets a percentage of monthly rent as a management fee.  

As said above, they be self managing and using 0% for a management percentage.  

If you want to compute a percentage down to achieve positive cash flow, then it is simple math juggled what is x and y, it is not a test on anything.