#1 - It'll be way cheaper to get (some banks don't charge anything, not even an appraisal fee). 

We charge 8% of the monthly rent, however, you may wish to budget up to 10% of the monthly rent.

I wouldn't make it a separate charge for a number of reasons.

Usually the first offense results in a cease and desist but the state COULD bring felony charges. 475.42 Violations and penalties.— (1) VIOLATIONS.— (a) A person may not operate as a broker or sales associate without being the holder of a valid and current active license therefor.

They'll charge you bogus feees upfront and nothing will ever come of it.

If I ended up installing the security door can I charge her for the installation?

We have an agent working for us and we even call the listing agents as well, however it always seems the properties are already in contract or negotiations.These properties are in a distressed area in Long Island, NY and we are calling on them legitimately the day they show up on MLS.Any advice would be appreciated.

I would think you'd have to do that as a water fee or something and not as rent.I don't think you can charge single occupants less than say couples or couples with kids.

If you've worked with a plumber a few times he shouldn't charge you for this. 

Plus, @ $50/mo, the tenant likely doesn't realize they are paying more than they would being individually metered since you only pay one customer/meter fee which makes up the majority of that charge...$35+ of it is likely a per-meter "customer charge" and not based on usage.