The primary risks at this point would be       1) to your lender, the risk of a margin call.       2) To you; underestimating the true cost of a project and cost overruns      3) To you; legal risk of securities regulations if you partner looses money. 

For one is that an appropriate price point for the supply/demand curve intersection?

There's a good chance the issue(s) you face has already been discussed and answered.Ask questions in the appropriate forum.

Keep in mind all this stuff is uber regulated, very detailed, far from simple.

Can regulations change?

A local investor will be best equipped to get repairs and renovation done at fair prices, set rents at appropriate levels, and help select qualified tenants.

Make sure any renovations comply with local regulations and obtain the necessary permits if plumbing changes are involved.

Definitely follow the regulations in the area and if permissible I would offer to attempt to find an acceptable tenant and terminate their lease when that happens but in the meantime they will need to continue to pay.

Just got off the phone with the zoning guy and he said since both of my lots pre-date the zoning regulations in the city, they're grandfathered in so-to-speak, which means I am able to build a single family on each one!

Be sure to understand the financing options out there for mobile home buyers and if you opt to carry the contracts on the homes you sell you should do some research on Dodd-Frank regulations.