Mainly the panel is in the basement and it would require a ton of work and paying for labor hours + repairs. 

Turnkey is just a promotional word and it, just like passive investing, require the same due diligence that any other investment requires.  

Only a few simple documents are required, including a valid passport, birth certificate, and proof of address.

In short, I can afford the additional $1100/mo cost of a second house, even until I rent it out.I have around $35K in HYSA and emergency funds that I could use for a down payment, but that's less than 20% which would be required for a conventional loan, assuming full purchase price.

This is required for most landlords in the city, as part of the rental property registration program.

However if you had done a warranty deed (or a special warranty deed if you still have a mortgage on it) instead, your LLC has a claim against you for the issue on the title, and you in turn can go back to your initial title insurance to fix it.Some title insurance will allow to transfer the coverage to an LLC that you own 100%, but not all of them do or they may require an additional fee.

One thing to consider since you are a California resident investing is the compliance requirements for LLCs incorporated in California or operating as a foreign entity here - the rules here are different than most states.  

With no proof required.  

A car forum that I'm a part of, and I know the owner of the forum, told me that the dedicated app required constant work and updates as phones and operating systems changed. 

When you tell them they will only get paid when the loan closes, they will disappear.If required, the only money you should ever send to the lender is for a credit check.