Newbie aspiring investor with questions

my wife and I have decided to move away from our hometown of San Diego due to rising home prices, stagnant wages, which basically makes it impossible  for someone to begin investing  without a large bit of capital, let alone the fact that properties rarely cashflow.

So far we have identified orlando, Tampa, and Jacksonville as the markets we would like to try  our luck. We plan using orlando to house hack while monitoring said cities for deals. Due to covid setbacks we may still be a 12-15 months out before moving, so as of now I am analyzing orlando properties as practice.

I had a few questions I was hoping you guys could help with.

1. Does living in an towable RV on property count as owner occupied? It would be a fixed cost and once we obtained a second property the RV would allow us to produce more cashflow than if we lived in a unit, and could be Airbnb'd once we no longer feel the need to live in it.

2. How does the down payment work on a second mortgage? We were planning on using an FHA loan to get 3.5% down on the first, but are similar options available for properties 2-4. And 5-10 are more stringent and require 20%+ correct?

3. Do commercial mortgages count toward your mortgage limit? Or is that only conventional  mortgages?