I offered $194,000 with the seller covering up to $$2,500 of closing costs.

What would is the normal amount to request for seller financing...is 20% etc. which should be reasonable and make sense for a purchase.

I am a 23 year old male who currently analyzes deals, meets sellers, and puts homes under contract for my investors that I work for.

That seems to me to be the time that you need outside expertise more than later in your career.If a deal is on the market (on MLS), the commission paid to the agents is already agreed to in the listing contract, so buyer's agent or not, the seller will pay the same amount of commission. 

Since both Buyers/Sellers do work with agents to Sell/buy real estates.

For the real estate side buyer and seller agree that a triple net rent of $45k a year is a good starting point

You don't have to take the lowest bidder and the contractors have ratings sort of like ebay buyers & sellers.

FHA requires a second appraisal for houses that are being sold between 91-180 days from the time the seller acquired the property and at 100% or more of the original purchase price.

For example seller wants $90k / house is worth $110k.

Do lenders view seller carry backs at the closing table as unethical?