For example: You buy a house 3 months ago as your primary residence and you find a better house and can afford both loans, is it possible to change your primary residence or do you have to wait a year and refinance? 

This is the problem, not that you could not afford 20% down.There was a 2% rule to quickly eliminate possible deals and choose markets. i.e $1000/mo rent for a $50K purchase. 

If people can't afford buying, then the market will change on the other direction.  

Had a house I sold on a land contract that the owner could not afford to do the repairs on so we put a Loyds of London policy on it until he made the repairs. 

There are many affordable schools which you can pay off while attending them.

The "Affordable" properties averaged $951 in rent while the Senior Living averaged $2,156The main point really is that the average rent isn't going to help you at all. 

While many people will be tempted to go with a relatively affordable brand- before heading that direction I'd suggest perhaps talking to some hvac SERVICE NOT INSTALL guys & asking what brands of mini split they can recommend... 

Remember you will need to figure out how much the house can afford to pay each month.

Offer well over list price with an appraisal gap clause if you can afford it.

Given your goals, you might want to  entertain the option of selling (flipping to an end buyer, rather than flipping to yourself. ) You could then use those funds to buy an already performing rental somewhere, since you are open to multiple markets.