This involves: Providing capital in a timely manner for pre-approved deals.Ownership is allocated in the following way: The asset manager owns 20% of each property.The other 80% is owned by those who provide the financing for the deal, with no distinction between leverage and cash.Partner’s percentage of interest in the company is the net percentage of capital contributed across all properties, multiplied by 0.80.When new assets are added to the company, percentage of ownership is recalculated.If cash infusions are required for major improvements not covered by reserves, we recalculate percentage.Distributions are paid quarterly based on profits, on the 1st of the month, based on a percentage of ownership.Now here comes the question: If I cash-out refi the property, is that my capital contribution, or his?

Allocate a certain percentage of your marketing budget for that, and give it a try, and then measure, and then pivot accordingly.

How much does the property management service cost (percentage-wise of the rent)?

One thing you should be cautioned about is the amount you can legally charge for late fees,check your state law it does vary and you just can't pick and choose a % or go over that limited amount.In Minnesota the amount of late fee charged can not exceed a percentage of the monthly rent amount. 

That is way more important than saving half a percentage point elsewhere.

Straight from the Fannie Mae Selling Guide - Verifying Capital Gains IncomeDocument a two-year history of capital gains income by obtaining copies of the borrower’s signed federal income tax returns for the most recent two years, including IRS Form 1040, Schedule D.Develop an average income from the last two years (according to the Variable Income section of B3-3.1-01, General Income Information), and use the averaged amount as part of the borrower’s qualifying income as long as the borrower provides current evidence that he or she owns additional property or assets that can be sold if extra income is needed to make future mortgage loan payments.Note: Capital losses identified on IRS Form 1040, Schedule D, do not have to be considered when calculating income or liabilities, even if the losses are recurring.Due to the nature of this income, current receipt of the income is not required to comply with the Allowable Age of Credit Documents policy.

@Liz Chen Don't go with blanket percentages as there are too many factors to consider.

For example, avoiding kitchen service cuts down on a lot of variable operational costs.  

Small percentages are so volatile in the equity department if your homes are in the beach area.

You can not buy true cash flow .As for the question, fixed or variable.......historically variable has always out performed fixed rates.