If you're good at math, then figure out the costs of borrowing short term as opposed to long term financing.Never finance long term assets with short term financing, finance 101. 

In my opinion this is tempered by the fact that the HOA will cover a vast majority of capital expenditures on a condo, such as roof, exterior walls, plumbing etc. and also landscaping, whereas in a house you must save for those costs. 

Putting curtains up to cover Windows, strong exterior lighting, security door(s) in rear.

This will leave both parties satisfied, as opposed to just you. 

I base it more on number of bathrooms, square footage, attached vs detached, exterior material, type of roof, slab or raised foundation, size and make up of the yard/landscaping, etc.  

There are also major tax advantages to fixing up a rental as opposed to flipping a house. 

I wouldn't be opposed to purchasing the Triplex on its own, but because of my low cash on hand (can't put 20% down) and the inability to get another low-money-down loan product (because I have to fulfill my 12mo at my current residence before a bank will offer that product) I'd have to have some portion seller-financed.

@Brandon Berkowitz Sounds like this is your primary...are you opposed to taking the six month to do the repairs and then apply for a HELOC?...

Would you paint exterior (it could use it)?

I think the property needs a lot of work on the exterior.