I have read that a homeowner cannot have two FHA Loans simultaneously.

Rent the unit out now to try and cover expenses while simultaneously listing it to see if you can get the price to make you happy to sell. 

They can do both transactions simultaneously and have your entitlement restored post-closing as they are the ones doing the refi too.Stay away from the lenders posing as VA authorities like USAA, Navy Fed, Veterans United, etc...they are great at banking and insurance, but frankly they suck at mortgages. 

It would permit you to acquire their replacement property before the relinquished property is sold.Under no circumstance may an investor be on title to both properties simultaneously. 

But,since I owe the original seller $300k, if we were to do a simultaneous closing, won't I have to show up with the $20k difference? 

As a real estate investor during these times, it is hard to both react to the problems within one’s existing portfolio and simultaneously begin looking for new opportunities.

I am thinking about holding this home, and long term renting the main 3/2 portion while continuing to short rental the detached guest house simultaneously. 

I would definitely test the sewers by flushing the toilet continuosly while simultanously running multiple sinks for an hour to confirm nothing went down the line. 

If I go this route, I would probably keep the mentality of investing in real estate on the side until a day that it can hopefully be my full-time job, I would just hopefully be more interested in the type of work than what I am doing now.I have also thought about somewhat of a merge between the two above options and trying to get into a law school that offers a part-time/evening program and working simultaneously as a real estate agent.

You can actually do a simultaneous close and use transactional funding for this, just as a wholesaler might do in some cases.