In order to have extra cash to help me pay off my student loans, I just wanted to explore the idea of using a hard money loan in order to finance my first deal and then later refinance it into a conventional loan. 

Unfortunately, I am kind of a dumbass and didn't realize that a conventional loan has to be the purchase price, something my realtor missed :/ I was under the impression that a 203(k) vs conventional with borrowing for rehab would be like the difference between a 3.5% down Conventional, and an FHA. 

If you have two FHA loans you will not get another one until you refinance one of them and convert one to a conventional loan. 

Can anyone advise me as to the minimum down payment on a conventional investment duplex?

  $125,000 - $40,000 = $85,000 less realtor fees to sell it, and will a lender finance it in it's present condition.Also, those pier and beams go out of wack all the time and maybe just adjusting them will fix it.Some of the older homes are jacked up with all kinds of automobile junk yard scissor jacks and Auto Zone bottle jacks, piles of rocks, stacks of 2 x 4's on grade, wooden shingles, tar shingles, etc... vs proper peirs.So maybe one of the renters (or one of their friends) crawled under there and removed the jacks to use on their car repair or sell at the pawn shop for beer money and now the floor bounces.Meaning get a 2nd opinion from a pier company (that's legit, has an office and a website, etc...) and have them confirm the ROT--if any.Because the floors do rot (sometimes) and also the piers go out of wack and sometimes also sometimes disappear into thin air--and no one knows what happened to them.Getting a 2nd opinion on if there is rot--with cell phone pics of it--would be smart--if none then adjust/replace the jacks.Good Luck!

Conventional.

Conventional 20% down How did you add value to the deal?

@Charlie ScheidererI believe that No conventional lender will do a drive through appraisal.

I have seen that I may need 15% down for our second property, is it possible to get a 5% conventional loan on a 2-4 unit?

It looks like you used "conventional" financing with that rate.