I hire an attorney for all my rental properties.  

Also, never attorneys, paralegals, health care professionals, etc.

You can also work directly with a tax attorney or CPA who is familiar with these plans.All 401k plans must remain current with changes to the tax code, so you will want to have an ongoing relationship with a legal resource that can provide periodic amendments.The advantage of a quality firm (not just a document provider) that specializes in self-directed Solo 401k plans is that you will have access to training and consulting advice so that you can operate your plan within the framework of the IRS limitations.

Recent/current renters include:well established attorney who went through a divorce/medical issues - $850/mo;IT professional, 15 years with same company - divorcing - $900/mo for bedroom at lake estate;IT contract worker with home & family elsewhere - $550/mo - unit was "empty" 2 days from previous renter; This rent is more than previous real estate broker landlord got for entire house!

These would be held by an escrow company or neutral attorney, with instructions to record the mortgage/DOT assignment and provide the associated documents to your lender, if you default.If things go well, you would pay your lender, your rehabber would pay you, and everything would get paid off when the flip is sold.

We also partner with attorneys who offer the option of bankruptcy protection, expecially important for homeowners who have equity.

It might also be advisable for you to hire your own attorney to negotiate with the city.

As for you and your parents arrangement, you may want to seek the advise of an attorney to determine your agreement between you and your parents regarding the money.The HELOC is relatively a simple process.

2) Since there will be at least one person trying to get that easy post to rack up their post tally by briefly and ambiguously  says "go see a state specific RE attorney," one tip that I would appreciate that comment at least say which state's laws I should be concerned about, and thus, know which state to find and attorney in?

I always suggest a good ERISA attorney to consult and set these up as there are issues that should be addressed at the outset as well as ongoing issues to remain in compliance.