A low price would be important but not too low (so that it raises buyer concerns) and ideally a brand that is well known and liked by MH buyers. 

What are the red flags and concerns?

I’d love any advice or tips for a beginner.

I‘m also concerned that the boyfriend and girlfriend may break up and one moves out.

I can’t speak much about other markets, but as someone who started off in Columbus, and grew up in Cleveland, i would say that the Ohio market in general is a very beginner friendly state for investors. 

I am currently marketing the office space but am concerned that the 3 residential units make it unappealing to serious potential commercial tenants.

Start with BiggerPockets Ultimate Beginners Guide (free).

(if I refi and pull out the equity it makes the CoC negative for the next 3-5 yrs)1031 option: sounds good, but I am concerned about finding the right property in the timeframe and my inexperience with this  creates risk.

Quote from @Erica Calella: I could see why you are concerned here, but if I was in your shoes, I'd try hold out as long as possible before jumping ship. 

In most cases many beginners do so their risk is low.