And someone jumping into this as a complete newbie can expect that they have a decent chance of making some expensive newbie mistakes. 3) On the other hand, I feel one of the main advantages of passive investments (via syndication/crowdfunding) is that I can hire a manager who has years more experience than I can ever hope to obtain myself.

Pacing yourself is key, especially as you get hands-on experience managing maintenance and tenant dynamics.Since you have a strong W-2 income, you're in a great position to leverage creative financing options as you grow.

Always loved to work with my hands.

Risk goes hand in hand with the amount of money you stand to make.  

What would you do in my shoes  If you are talking about $90k profit before transfers in Cumberland...without question id sell it instead of holding it. 

I transferred the money via EFT (the transfer instructions had no reference to Lendbase - red flag), and asked for a receipt, but was told that their customers rarely ask for a receipt. 

Get in front of tired landlords, who may offer you a hand up.  

The value of cash in hand today vs cash in hand tomorrow is significant and you should account for that for both sides of the transaction for any deal that you make. sellers going to do their best to sell their asset for max price.

If you can access the wall cavity, adding rock wool (mineral wool) insulation will make a big impact by reducing vibrations and sound transfer. 

Make sure to keep backup documentation for each transaction if possible and transfer the balance when you return.