It does not translate to real money world therefor it's use is highly restricted.If you want to see how restrictive try buying a coffee with bitcoin.

Unless, of course, the offer is not legally binding.

What recourse do I legally have?

Otherwise you wouldn’t be writing about it here).From a legal perspective, are there ramifications from NOT kicking them out?

Aside from the immense guilt, you could face major legal problems.

Also, 10 year old renovations will most likely not achieve market rents, which means that any buyer will need to invest in renovating the units)Is the basement unit a "legal" basement unit?

So I have a few questions. 1) As I have never done commercial real estate, am I legally aloud to help them?

Is there a way to do this while legally protecting myself from liability (i.e. having them sign a waiver)?

If you can keep your cool, and let the courts and the legal system do their job, then you can do it. 

Getting answers to those questions will determine the amount of capital reserves you'll need to bring in addition to the down payment, but I'd guess at a minimum you'll need $15k, which drop your returns to the single digits until you can increase rents.I'm not 100% sure of the legality of the county's laws regarding sun setting lots, but you could reach out to the state's manufactured housing association and potentially get the two lots back if you agree to infill them with new units.