I'd just send them a move out list of what they need to do and if your lease states that you can show the place (with proper notice), I'd remind them of that and try to book showings as close together as possible to minimize the disturbance to the tenants. 

There are plenty of good books about note investing to explain the real estate and financial side of the business.

Not entirely sure what avenue of real estate investing I want to take yet so I've been reading lots of books on the different strategies.

While a lot of what you'll learn will be from experience, I do think there are some resources to increase your knowledge base and give you more confidence as you take your next steps.One book I'd highly recommend starting with is The book on managing rental properties. 

My first bookings were all for the whole unit so eventually I just gave up marketing as by the room b/c it's easier on my to do whole unit.

The insurance market is very tight right now especially on older buildings.Many carriers who have policies on the books will not accept those same properties as "new business" or if they do the rates are 2x-10x what the current policy premium is. 

Finally (after 7 years of reading books, research, podcasts etc) jumped off the cliff and bought a major fixer upper for very little money.

I see the idea and I think it's great, but going all in on a theme is going to make a potential guest stop scrolling and book with you instead of anyone else.

I am currently paid out a % of each booking as a co-host on airbnb automatically. 

I've seen a lot of demand for MTR bookings in a few areas.