Better pay the PM fee, then you get a professional you don't have a friendship at risk, and they get the midnight calls, AND you can write it off as an expense. 

Have written agreements (that are reviewed by an attorney) and keep the friendship as a separate thing.  

It can still work, and could be beneficial based on your existing friendship, but don't let money ruin that.

Today's close friendship or romance or clique can be tomorrow's domestic screaming match, bothering all the other tenants, and causing “good” tenants to move out.You can find quite a bit of news articles available on the resurgence of co-housing and micro-apartment type living.

Never mix business and friendship, Greg.

So a good "friendship" with the building inspecter is needed.

Any other gifts are pushing the line on friendship.

You can be pushing friendships too far when you are holding your hand out, so even if it is offered, consider it a friendly offer more than a business relationship, I suggest making them offer at least three times before really considering them in a business dealing.....you can set the stage for the offers to be made, but don't just ask and never beg!!!

A friendship has developed over time.  

Firing someone is hard enough, firing a friend typically means ending the friendship while you're at it.