Or is there something I'm missing from the complicated section 8 process. 

It's important to note that only judicial foreclosure sales will eliminate federal judgment liens (other than federal tax liens) in favor of the United States, subject to a right of redemption (1 year).

It is admittedly a complicated system but can be an effective asset protection tool if used effectively.

Problem solved.It isn't like a fridge or washer take a complicated hook-up....just plug 'em in.

To be sure, we can complicate the argument by introducing the tax advantages that real estate investment such as depreciation etc…but we won’t go there now.so, if we assume that the appreciation of real estate in general is going to be negligible over the next several years, as a prudent investor you should look for properties that can cash flow at the minimum rate of return equivalent to or better than the rate the bank would give you on your money. 

Are there any building regulations for quadplex that are more complicated compared to duplexes?

The ROI on solar is more complicated than a one line answer on a forum post. 

Sounds overly complicated with little-to-no benefit.

Assuming that is close to correct, I think the owner will likely find this complicated and make it a hard sell.  

Complicating the matters are 3 tenants, non of them paying rent.