Now, I know I was getting nowhere near the 8-12% property managers charge.

From my understanding, a lender will charge a LLC commercial interest rates versus individual home purchase interest rates. 

Does a landlord in San Jose, CA  have the right to charge a fee if I choose to remain living at the property on a Month to Month basis? 

I could tell that you could have charged more for rent but you weren't.

If there is an emergency, break in and charge the tenant.

And do you charge 3 weeks for 1 month or something like that for this type of renter?

Now, with new builds, you are correct that there are more warranties in place, and less work needed down the line, but as an investor, the premium you are paying for that, charged by the developer, is not worth it.

Lying about neighbourhood quality, rent amount, cost of repairs, repairs charged but not actually being done etc.

They’ll do them on investment properties and they don’t charge any fees at all to set them up. 

Luckily, I set aside a portion of the monthly rent for unexpected repairs/issues.