Can pay a flat fee listing service... 

In the Boise,ID metro we generall use 40% as a general quick analysis plug. 8% for property management, 5% for replacement reserves, 5% vacancy, etc.

One suggested signing up for their service plan ($20/month per apartment) which includes one annual boiler checkup prior to the winter to avoid issues like mine and small discount on regular plumbing services (50% off of service call charge of $95 and 10% off labor costs after).Is this something you guys would recommend?

I am a Field Service Engineer, I repair/service Nuclear SPECT camera's.

The previous buyer was also an investor who didn't have enough reserves and got hit with a couple of violations on illegal rehab. 

I think it's a good idea to take caution and keep cash reserve for rainy day (also gun powder dry to get cheap property in down turn). if your portfolio is sfh then you going to have a bit harder time.

The gas company employees are killing there business here.One thing you need to consider is if the house has enough power service to feed an electric hot water heater, you may have to upgrade that. 

No different than people accepting poor service at a place of business by continuing to patronize it and creating a sense of norm around accepting poor service.

Where will you get the down payments, make debt service, manage, etc?

The property currently cash flows me about $790 per month after debt service and all expenses and the property management fee.