The wax ring could be shot, allowing water (and possibly sewage) to leak out around the ring and soak into the floor.

Being a 1960s era, it will have everywhere.  6 inch tile floors, hot water pipes, countertops, etc.Would check on that before diving in.

Do they look good but need new roofs, have soft subfloors and ancient water heaters?  

Are bills like electricity and water something that's figured into weather or not a property is self sustaining?

Then we also have to track water bills to ensure tenant reimburses us for paying them.Is there an easier and more automated way to track and quickly tally the security deposit refund due to a tenant?

I’m not aware of major plans for that specific neighborhood, but it does abut and is near very major planned and ongoing developments (Ybor Harbor, Gasworx, Ybor District, Channeside/Water Street).It will garner more interest as more progress is made on those developments.

Michael, I've been reading about hot tubs and "hot" is in the name, but they can be cold water tubs too, so the temperature can be set as the season varies.  

You seem to be relying on second-hand stories to form a narrative that doesn’t hold water.

An IRS lien, code violations (weed abatement, grass cutting, boarding windows-doors, and demolition costs), HOA fees, water- sewer bills all go along with the property providing the property has any of these. 

Stepping into these waters is already an intimidating process.