If you control your water drainage from roof and reduce risk of tuckpointing the upkeep will be less so should be more cost effective

maybe the roof was just done but the furnace is 25 years old. 

Yes some systems are more but some are a lot less like Roof, etc.

Brand new water heater but tenant is calling in about no hot water heater, leaking faucet (which were new and installed by seller), leaking kitchen sink.

Each unit extends from the foundation to roof and has open spaces on at least two sides.

You get a few doors but only one roof/boiler, to fix. 

There is no sub-floor and due to a leak they were exposed to a wet crawl space. 

Yes, anything that does not require a permit is fine.......but not electrical/plumbing/framing/roofing/etc

The AC unit was leaking for several weeks and I had to mop up the water almost every day.

I know about HOA fees and alot of condos/town homes only alow a certain amount of renters, but on the flip side i think my CAP EX would not be as much because im not responsible for the roof, snow removal, yard keeping. any thoughts would help, thanks.