In other states, HOA fees are minimal, but here in California as you have seen, HOA fees can be us to $500.

Without bringing up the lease again and aggravate him even more as he wanted to talk to his attorney (according to what he said/presented he is a kid with rich parents with attorney), what some other ways to minimize the situation (ensuring no random security issue / damages on house and car), get my garage and driveway back, and get him to leave peacefully as soon as possible?

You’re able to minimize exposure to risk of market shifts and regulations changes and still make a good return on your minimal investment.

If you ever get a notice of a move out be ready to turnover that unit and get it move in ready as soon as you can to minimize the down time.I do understand the "house hacking" loan but 3 or 4 unit house would have decreased the pain of a vacancy. 

The building was also laughably listed as Class B, "minimal management", "easy to manage." 

The home is one owner since 1955 with minimal renovations so will make for a drastic change.

The increase of the basis will help you minimize the taxable gain when you eventually sell the house.2) Improvements made on the rented side will also be added to the basis, but you can depreciate the improvements on the rental side and deduct depreciation against the rental income.

Again, the goal is now to minimize the cost of this first home, and to acquire another SFH rental in the area in the next year or so with positive cashflow.

Can he spray with minimal prep work?

All are solid areas with minimal riff raff.