It's 2018... days of damaged roofs due to solar installs are long gone (unless you have a ceramic tile roof or something that easily breaks when stepped on)You can easily reduce your power bill down to just the utility's basic charge, typically 5-10 bucks per month.

What is enticing to one investor might not be for another one, so is a very difficult question to answer with such limited info.Also, I don't have experience with multi-use resorts so I'm not quite sure about what is a "typical" structure used in that niche. 

Typically terms I've used are 5% interest, 30 year amortization, 5 year balloon.  

Typically an ADU is inferior in size to the main improvements.

---one has been in place about 1 year; just started a new 1 year lease; seller says he is a PITA and it typically late on his rent, but pays the lease-ordered $25/day late fee-Seller said he wants to enter an owner carry / owner finance scenario, as he wants to spread out his tax liabilityHere's where I need your advice:-Seller paid $150k for both properties four years ago. 

Check out this series of articles:  Flipping and Rehabbing"Hard Money Lenders" are a typical source of funding for fix and flips. 

Typically, investment properties are valued based heavily on the income capitalization approach.

On the B to C transaction, is "C" buyer typically another investor with cash or private money?

The buyer doesn't perform you typically have to just go file an eviction just like with a tenant except when is the bond for deed filing eviction it will usually take about 45 days to complete the eviction process.I've done a few over my time both buying and selling and it's not that difficult.

The Austin area housing market didn't care that February is typically a slow month.