I've been pre-approved for a 3.5% down FHA loan which is what I would prefer to do because the low money down but with it being an FHA loan the house is going to have to be in livable condition to meet requirements for the loan. 

You also may want to require in addition to down payment from the buyer 6 months to 1 year mortgage reserve payments in advance.Do not set your interest rate below market or you could get hit with imputed interest charges on taxes.No legal advice given.

Make it known that this new occupant NEEDS to be approved by the credit check and background check, otherwise they are violating the lease.

I do not have a realtor/broker license and have recently been reading that it has become harder to connect buyers and sellers without legal repercussions because of this.My question is what is the best way to connect a seller to a buyer without infringing on the legal properties that licensed realtors have dedicated to them?

What you're essentially asking for is legal advice, and for that you should seek out an attorney knowledgeable in this type of law. 

I  am in the middle of opening a HELOC which should be approved for 10-15k (depending on the appraisal).

No attorney can really help you as the bank has no responsibility, or perhaps even the legal ability, to negotiate anything with you.You have no recourse against the county or the courts.  

I live in San Diego, CA and would like to see if anyone can recommend (personal experience preferred) an FHA approved lender in the area. 

Trying to figure out best course of action to get the roommate out legally as well as hold the owner accountable for not delivering the property on the date per the contract.

The overall goal is to have the lender approve to sell the property for less than what is owed so the homeowner can walk away not owing anything and can avoid foreclosure.