I didn’t care for the heat and humidity but found that the people were kind and respectful and I LOVE how Jesus is not a dirty word there.)

It seems like a lot of money to spend on a low-end heating system, but the other options don't sound good either.

@Dale Miller  FHA, VA and USDA appraisals are far more difficult than for a conventional loan.Appraisal for a conventional loan is looking for the value of the property and to ensure that all major systems are functional - water, sewer, electricity, heating and AC.FHA/VA/USDA does the same, but will also fail for anything that can loosely be interpreted as a health or safety issue. 

Get the space air conditioned or heated so mold stops.

If you work on plumbing, heating or fire sprinkler systems you must have either a class I or Class II license. 

I think those would be good enough margins.However I am still concerned that when I average the heat bills it comes to $200 a month. 

Things that increase or decrease your rent are things that cause the utilities to go up or down, such as size, number of shared walls, utilities, appliances, type of heat, any energy efficiency features, etc.

@Christopher Munn No reason to wait-it is heat and you need it now-right?

The listing says "separate electric," but there's a gas hook up and forced air heat is noted.

A few minor more tactical points -  is the duplex metered where you can even make each tenant pay for water, electric, heat?