If you do not have the capital then you should consider partnering (Joint Venture or Syndication) with someone who does.

I'd share that if I did, I'd be prepared to pay them to vacate.

If the water would have came back bad we were prepared to replace the pipe but was told this repair would be around $8K. 

You just buy as many as you can and then figure it out, there is no way to prepare, you just deal with it.

So unless im prepared to lawyer up 3k just to try and get some of it back the answer "just walk away from your deposits, im trustworthy" doesnt work for me.I have prepaid for work from big names, Lowes installs etc.

How can I best prepare for managing two rental properties, including handling maintenance, vacancies, and tenants?

I usually talk to a dozen banks when preparing to make an offer or just get a property under contract. 8 unit is just south of 20 by the fairgrounds.

Congrats on preparing your property for an STR in San Diego!

Is using a self-direct IRA to fund this venture a way to defer taxes until retirement ?

As a former planning commissioner the people AGAINST projects are the loudest so you want to make sure you have a good pulse on what your neighbors and the louder people at public hearings stand so you can be prepared ahead of time.