I am not against paying for coaching but I believe it is most likely to pay dividends if 1) you know exactly what aspect of RE you desire to pursue and can find a mentor that is a very good fit for the RE you want to pursue.  2) you are very motivated.   

This investigation is critical to assess whether the investment is economically feasible and will generate the desired revenue.

That need could outweigh their desire to protect your best interests.Not saying there investment here is a bad thing, per se, just raising this point so that this one element of the deal doesn’t tip the scale to you investing if you otherwise might not.

A desire and ability to share their knowledge4.

The fourth question is what is the most efficient and cost effective way of obtaining the desired knowledge and experience and what is the way that has the least downside risk.  

I’d be interested to hear how people optimize their portfolio after achieving their desired scale.

. - in RE I can depreciate the holding and if desired I can accelerate my depreciation.  

I would try to get more units if it were me, however if a deal is desirable and its a duplex I would run with that.

Oh yeah, also a LOVE of the real estate industry, and a burning desire to succeed.  

Make sure you truly understand your goals (desires).