Your contractor being classified as an independent contractor is fairly simple, but not the most important aspect.  

And we haven't even seen it all as we have not had a tenant threaten to sic their girlfriend on us like @nathan G. has. 

This gives you the opportunity to classify a utility bill as that, then put it towards a specific property. 

Discuss the impacts on classifying it as an asset or stock acquisition because the buying party will also have motives for classifying the purchase one way over the other.

@John MaloneIs there a path to transfer/re-classify multiple properties from a single owner to that of the single owner plus his heirs that doesn't result in immediate tax implications?

Other online classifieds endemic to the area?

I then start looking at the online classifieds for deals.

The investment activities you plan to engage in with the Solo 401k do not classify as that self employment.  

A property earlier in the year was converted to a mulitfamily and was sold 200k over the ARV of the properties classified as a single family in this neighborhood.

For newly constructed, purchased or renovated properties and also retroactive generally over the last 10 years, building components are properly classified into individual units of property and accurate recovery periods for computing depreciation deductions.