Looking into the mini split systems it seem like this would be more energy efficient since you're only servicing rooms/zones not the whole house. 

He tells me about them all the time and complains about the junk mini van in the driveway, etc, etc, but they always pay on time!

Kinda like a mini Cruise America!

This masterclass took so many hours of dought and fear, self educating, podcast, books, mini trainings, and probably several years of trial and error to figure out, and crammed it into 10 weeks or less.

We have yet to furnish it and plan to renovate the back yard to make it a mini oasis for renters.That being said, do you have any words of wisdom or things you really wish you would've done or known after you acquired your first STR?

Same thing with grade - your house should sit on a "mini-hill" where the ground in every direction slopes away from the house, ideally for a long distance but at least 10-20 feet.

I went through this exercise after taking a mini MBA program at Stanford before I landed a role at Google. 

A heat pump is used as an alternative to gas, so your concern about electric base-board heat is invalid...the entire heating system would be electric...Heat pump technology has come a long way and these things are good at providing heat to a property with a 3rd floor as long as your ducting is good...and more importantly, your R-value...I would look at 1)- better insulation, 2) extending the gas line and adding a gas furnace, 3) installing a PTAC unit, 4) Installing a mini split...or baseboard heat...its actually a really good heating source...and think more about hydronics...in my opinion hydronics is absolutely the way to go in almost any situation with boiler technology...Best of luck. 

I used to keep extra everything at every property (Mini soaps, Toilet Paper, Paper Towels, cleaning soaps, coffee cups, etc) but realized that I had a LOT of cash tied up in stuff that would only someday be used.

Following a couple of months of slowing activity, the real estate market experienced a mini-boom in November.