IF something breaks, will it affect their % of income? 

We had the plumbing break down and had to install new PVC plumbing Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

If you are going to charge your boyfriend rent, what if you break up?

Time is money and money makes or breaks your business.

Perform a Break-Even Analysis: Determine how long it will take for the savings from the refinance to cover the prepayment penalty and any other refinancing costs.

you'd have to break it down to some like for like comparisons to come up with a more "general caprate for a specific asset class" or something like that.  

For 7 months straight I was -$300 to -$700 a month because of repairs called in by the tenant (tenant   wasn't breaking things as confirmed with Property Manager).A 100 year old renovated house is going to have problems.  

If they all break after 6 years and 1 day. 

Typically I am seeing investors put down 30-40% to break even or cash flow a bit, so that is about the same as your 80% coverage ratio. 

I would also be worried about the park rules and keeping my guests from breaking them.