He was a former professor and has online courses that are good to have.

(G) Acceptable forms of payment of Rent (including Additional Rent) are ___ personal check, ___ cashier’s check, ___ bank check, ___ money order, and ___ the following online/ACH payment methods ____________________.

The answers to most of your questions can be found just by searching in BP or online. 

They claim to market on dozens of online channels, and they seem to know the right amenities to feature, have great design, services, experiences etc.

I'm going to take your comments about the communication to heart. 

Are you currently working on lining up funding or looking at potential properties yet? 

If you've got to ask a question on an online forum about managing an out of state or out of country renovation, you aren't ready to do this on your own.

Have proof on hand (easy enough to find) online of the missed tax payments and any documentation that supports that he specifically didn't pay his taxes.Probably a simply mistake on his part, but now if he wants to develop on it, he either has to land lease it from you or buy it back.I'm not sure how the whole tax deed thing works, so that would be something you have to figure out between the two of you.

I offer an online payment portal to submit rent payments via ACH or CC - they "couldn't figure out how to use it" so I set us up to accept Zelle payments.

If you don't get access to the property before closing it can be tricky but if there are recent photos online or you can walk through before and take your own then it is much easier.