I prefer to stay in mostly owner occupied areas because it yields a higher quality resident that's more consistent over time and the homes typically appreciate at a faster pace. 

So all you really need is right here on Biggerpockets.I don't believe that these courses are worth much.

Was the cost to build worth the additional rent/value the property sold for?

Typically, the seller wants it done fast and cheap, which often does not equate to the quality you would look for as the owner.But, it is possible he wants to do the work because he has top quality contractors that will do the work well and for less money than you could yourself.  

Typically I use Google to get quotes and vet the top 5-10 search results.

@Shawn ChervinskisThere can be no direct or indirect benefit between you and the plan, and the fact that you would occupy a unit of the duplex is a 100% deal-killer for an IRA or 401k.You could use a Solo 401k to purchase a property held entirely by the 401k, and to which all expenses and income are attributed to the plan.A 401k (or IRA) can use non-recourse financing, but typically non-recourse lenders will want to see more like 35-40% down and a minimum of 10% cash in the plan for reserves.

Typically private lenders won’t you CJ long periods of time unless it’s astronomical Interest as money is constantly devalued and $100k today vs 20 or 30 years from now will seem the money essentially worthlessOnly reason it works for banks is because the money they lend actually doesn’t really exist they make it up due to fractional reserve lending

Worth area.

I'd like to continue to sue for missed rents and damages, but I have no clue how to go about it anymore and don't know if it will even be worth it after the ~$20k she'll owe in both, anticipating an attorney will charge close to this or more. 

So it's really a matter of it not being worth their time when they don't want to do it.