-Vacancy, maintenance and capital expenditures will need to be accounted for-Will you self manage or use professional mgmt ?

To be honest the monthly payment doesn't sound outrageous given the possible items covered, but who know without the accounting...and any buyer should want to see that accounting when you sell, so sort the issues out now. 

If you go with the partnership route1) You need to manage the money going in and out of the business bank account.2) File a partnership return and be responsible for issuing K-1's3) make distributions to you and your partner for cash flow that you receiveYou will likely spend many hours on a nice gesture.I may want to consider instead to give a christmas gift or a bonus for early completion of projects.

If you have checkbook control you’ll have a bank account with a bank that has FDIC insurance up to $250k per account.  

Sellers had multiple "accepted" offers and all were placed in interpleader accounts. 

You are basically removing the cushion of a savings account and using the HELOC instead as your bank account.

I compared other properties in terms of age, sq ft, acres, beds, baths, basement, garage and a subjective measure of interior condition.I have a huge problem with the automated comps (Zillow, RPR, etc) because they could not account for the interior condition. 

They also said that the amount the property could pull in rent was much less than the amount that Rent To Retirement claimed it would be.Rent To Retirement also did not account for any amount of money for closing costs, they accounted for maintenance costs being at 3%, which is considered extremely low.

Some charge based on account value, others per transaction, and some use a combination of both.

Happy to help and I have some professionals in UK (solicitors, accountants) that I can send your way.