Or would it be better to simply partner with them, they are friends of mine, with the repairs for a percentage of the profit?

Implementing systems to make your portfolio more profitable is key.Congrats on all your success!! 

If the 2nd project would go as planned, I would profit the same amount I just put down for it.

There's huge liability and usually not much profit in it.

The duplex is not profitable currently due to the increased mortgage payment and I’m set to lose about $350 a month.

I manage both long-term rentals (LTRs) and STRs, currently operating seven STRs, all of which are profitable.

When the economy suffers as a result of too much of a contraction, debt payments are harder to make, etc, then go through the cycle of loosening it again, devaluing the currency so debt payments are easier to make, and banks can profit higher than before.

I have an opportunity to build mixed use apartment and I want to get an expert thoughts on the projections and what should I be spending on construction to make this project profitable.

I find there is more profit to be made and more flexibility if you use your own funds. 

I plan to build versus buy because Im currently working for my father, who is a general contractor in Fl, and will save on the construction costs because I can do most of the work for little cost other than materials. it would be minimum labor cost and no profit cost from contractor.