@Joani Riley Generally it can vary slight by state but most conforming loans are generally the same. 

I tried to do it with out knowing that. and an auctioneer turned me in post haste.. so had to conform.. 

Big banks are a pain in the a*# when it comes to underwriting though.You are correct that it is still a residential loan, but because it is a multi family, it has to conform to Fannie Mae standards which are sometimes more stringent than SFDs and owner occupied.

For reference these are non-conforming loans; also called “portfolio loans”.

The property is a legal non-conforming duplex that does NOT have separate meters for utilities. 

Several of the inspections resulted in non conforming work a d an estimate for correction was included.The least expensive event was around $500 (inspection for utility), up to 10K (report, repairs, inspection) addressing issues.Knowing a good electrical contractor can solve some of your issues.The issues you presented,  in my opinion created a voidable contract. 

They often hold their mortgages in house, don't have to conform to F/F rules, and therefore have a lot more flexibility. 

Trailers should still be grandfathered in, just because it changed owners doe not give them the right to come in and make you move the trailers, if you were creating new spots then you would have to conform to the new law.2. same as above, county can not just come in and say you need to more parking spots to an existing building that has been approved for the amount of spots, the parking is grandfathered, the only reason they may have to add two spots is if during the time they owned the property they added an apartment to the building illegally and they were now caught having an extra apartment.These are zoning / building issues, you can always call the town construction department or zoning department and ask if there are any known/ outstanding issues with a property during your due diligence.

I 100% agree with @Nicole Heasley and @Jason Snider , AirBNB a room in your house or rent, or look at selling (especially if you have been there 2 years or more and have equity built up) OR keep as rental and look at buying a 4 unit (largest that gets a conforming loan) move into one unit, rent a room AND rent the other 3...GO CRAZY, you have an amazing income at your age...use it (be smart) cut the lifestyle to get the extra t pay down the debt. 

At best you are paying full market value for a property that is non-conforming and needs work (4 beds with only 1 bathroom).At worst, you are paying 10% interest (Higher than even most hard money lenders) and you are renting to your friends (It's best to never mix family, friends and business).If your friend stops paying rent, do you feel comfortable kicking them out?