Most common treatment is I-beam that pushes the wall back.

This may sound simplistic, but you need to get laser focused on exactly what you want so that you can then plan your marketing campaigns.2.  

If you are dealing with an addition built on 12" beams (or if the original foundation is old and not built to current standards), the repair company might not be able to push the piers down to refusal depth or psi due to the beam not taking the load, thus leveling it, but not guaranteeing it will not continue to move in the future, thus not providing warranty.9.

Here's the plan I've decided to laser-focus on:1. 

The closest thing there is to that rigth now is laser scanning but this is super expensive (like $3k-$4k per visit).

Some deal killers (In my opinion):Large scale foundation issues (one or two pier/beam repairs isnt a big deal)Poor location (no one wants an amazing house in a terrible neighborhood)Price. 

I am thinking about to change it into a game room with a ping pong table, but there are some support beams in the middle and the ceiling is low too.

The FHA loan is very challenging to use right now as a house hacker, so you have to have laser sharp goals to make sense of using it.

Should I get laser focused on buying at auction or keep buying from wholesalers?  

That will kill every project right away. 4) If you come across a 'mandatory', like a  rotten beam that must be replaced, then put in writing, in great detail, exactly what will be done, exactly how much it will cost, and exactly how much time that will add to the project.