So far as they are concerned, no billboards, no manufactured / industrial housing, and there is a demolition delay, were I to choose that route.

I'm not a lawyer, but I'm sure some of this will help if you choose to proceed with an eviction or go back to collect unpaid rent from either party. 

I need to choose a focus. 

If you choose to pay yourself or not that is up to you, but if you are looking to sell these one day it makes sense to factor in the management fees.  

May be worth having something in your lease that the tenants sign that the attic is not considered a bedroom and any and all liability will be assumed by the occupant if they choose to have a person sleep in that bedroom.At that point, you’ve covered your bases and hopefully have yourself a layer of protection in your lease.

Depending on which of those you choose, you'll then do more investigating into areas, budgets, etc.If you want to do your own rehabs, that's a pretty major undertaking that requires a lot of planning and networking and negotiating.

There is a difference between not paying rent due to true financial hardship and choosing to not pay a landlord even though you have a job and money. 

Is it safe for the investor to just contact the county and pay the next year taxes when they become due and would the original tax lien amount and subsequent year taxes paid by the investor all have to be paid if the owner chooses to redeem?

A few tips where ever you choose, pick the right team.

@Russell Brazil i've got 4 units (one currently vacant after a rehab and being advertised) in what I would consider a C-B neighborhood in baltimore. 1 tenant is on govt assistance with the other two paying market rent. additionally, one of the tenants is coming up on the end of their leasing period and will have the option to stay if he chooses.