.- Yes, there is increased liability; however, if you take earning your license seriously, it doesn't take much to understand what must be disclosed, how to disclose it, etc.

I have a self-directed 401K (solo 401k), and purchasing real estate for buy and hold.However, I would like to grow it by taking after tax dollars (W2) and issuing myself a promissory note of 50K but instead of doing “minimum” payments of prime + 1%, could I artificially increase it to say prime + 5%?

Because of the prohibited transaction rules, doing so could be a violation of the rules, or at the very least, would limit your flexibility with the investment and increase the chances of a prohibited transaction occurring after the investment is made.

If they do this correctly they can do it with multiple properties and keep increasing their wealth.  

The lease is month-to-month.I’m looking for a recommendation on how to increase the rent.

Inherited tenants increase risk, as they were not screened by you.

Zillow estimates an 11% increase in home value.

I enjoy my profession but i am very interested in trying to increase income without having to work more.

I have already got notifications from vendors to expect price increases starting Oct 1st, 2018.This will have an impact of all aspects when flipping, renovating and maintaining rentals. 

Focus more on building personal savings and increasing income (is there a possibility of picking up a part time job?)