I now have the opportunity to live in South Lake Tahoe in my grandparents home for free (incredibly fortunate to have the place to myself as it is a second home) and am wondering if I should seek out a brokerage here to perform as an agent as I build my wealth to eventually invest.

You start small, eat at your level of sophistication, perform, give investors great returns, and rinse/repeat as you work your way up the ladder. 

Sure, you can always sue for specific performance but, again, there's not that much at stake.

Additionally, the $9,000 is more than I paid the general contractor for what labor they performed, so I'm not sure where that leaves me.

I've paid many professionals who royally messed things up.At the end of the day if the work performed concerns you, make sure you have a good building inspection done.

2) Performance - How have your past deals performed?

My recommendations to anyone who is in corporate and wants out - Do not perform for the audience who does not belong to you. 

I found two buyers willing to buy my contract to purchase as my obligation to perform had not expired.

What would happen if your buyer wanted to have your licensed GC company perform the work?

I think it's ok to buy and not get a great return, but don't try to convince yourself a property is performing better than it is.