Ideally looking to keep the house as my primary residence for at least a few years, then either use as a rental or sell depending on market conditions. 

These are the terms of the contract which I would offer:$20k - Option fee$2100 - monthly rent, $450 of which goes toward equity at the time of purchase.Buyer / tenant on the hook for all maintenance from day 1.2-year lease term.Sale price is fixed up front according to 2-year value projection (present market conditions).

You'll have to judge whether the condition of the car is worth all this work, legal fees if any, and getting the car into working condition. 

what is the water piping, drains, electric, sewer and heating system condition?

While each real estate syndication is different, we typically see hold times of 5-7 years, sometimes longer.Real estate syndication deals have to allow time for property renovations, management changes, occupancy rate increases, and even market conditions to adjust.

This is my first BRRR, I officially start renting November 1, in the properties current condition, at $1800.

We both desire a partnership agreement to establish the terms and conditions of our new venture.

Property condition requirements are not as stringent as FHA so it's a more attractive offer to a seller but it also doesn't allow for reno like 203k. 

If you have proof of the condition of the property prior to move in, and there clearly wasn't an infestation problem you stand a better chance.

The more people who open it and stand in front of it for air conditioning or thinking about giving the dog a piece of chicken the harder it runs, the shorter it's life.Your picky tenant will never be happy.