From a selling standpoint there are 2 big concerns:1. disclose - you know there is an unpermitted room and/or any other problems (you said something about electricial).  2. the buyers loan/lender. 

Additionally, there are 3 units in this house and they are all leased until June of 2019 - so we couldn't move in anyway.Speaking with a mortgage broker, we were advised that - if we were to use a FHA loan as first time home buyers - for a duplex it would be 3.5% down.

I am always very clear that I am the seller/landlord/buyer.

Around here a base hit SFR sells for 80K and rents for 1100-1200/month.In this case, I would be the buyer's agent, do the searching and initial look-over of the property, run the deal (likely on my own finances through a commercial lender), and place/manage the tenants after closing.

Hi I am a first time buyer with hopes of becoming a buy and hold investor in the future and I am contemplating making an offer on a Duplex that fits all my needs as a family man but from the numbers I ran it won't cash flow (while I live there).

I got my license about a year ago to help with purchasing my own SFRs but so far had neither sold anything nor worked as a buyer's agent.

Obviously, it kind of sucks for us to discover foundation issues but a smart seller I would imagine realizes that he is just going to have to deal with this issue coming up again with the next buyer if he ends up sending you away so I am trying to hold my ground while being reasonable.

,I may be wrong but ...If you received a contract signed by the seller which you then had your agent revise before you signed it, then the act of making revisions nullifies the seller's signature and the seller would need to sign the revised contract.If that is how the series of events unfolded, I would think you never had a valid contract signed by both the seller and the buyer. 

The more competitive the more potential buyers, but also the more people you will be competing against to get deals. 

@Raymond Hill my sense is that due to the various costs and regulations involved, as @Brandon Ingegneri mentioned in his examples, it just makes more economic sense for builders to focus on single families than multis.I think it's related to the fact that most single family purchases don't make sense from an investment point of view because as an investor who's looking at income and expense #s to determine what you can offer, you're competing with owner-occupants who have very favorable financing and are buying because of the school district and because they like the kitchen and bathroom, not whether the rents vs. expenses & mortgage is profitable.In other words, because of the favorable financing and "use benefit", the buyers of single families almost always pay more per unit than the buyers of multi families.