Stay away from Alcohol, smoking and drugs and focus on improving yourself personally and  financially.God Bless you and i pray that you will make the best decisions for your future.

Paying up front makes me nervous too, is there any chance this is a story and they are really drug dealers etc? 

Best thing to do is "explore the space cause I got a fever and the only prescription is more cowbell"Thank you for taking the time to read this long-winded answer. 

The neighboring 4-plex might get overrun by drug gangs.

However, this only applies to dogs that have gone through the proper training and have a prescription from a doctor.

You are the property manager, maintenance guy, appliance repair person, marriage counselor, cleaning person, rent collector, salesman, advertising manager, internet and cable tech, website manager, electrician, lumberjack, garbage collector, city liaison, chauffer, check cashing office, bartender, job referrer and finally a pre-employment drug screen collector. 

I get the lease and tenant applications from the owner for the purpose of determining who's in the property (drug dealers, scumbags with previous evictions, etc) and so that I can see how long is left on their lease.

I figured a drug dealer.

Yes people that are completely unemployable are all the sudden going to stop selling drugs, stealing, and carjacking. 

There are contractors who will pull permits for you illegally just as there are drug dealers who will sell you drugs or people you could by stolen guns from, all of which are illegal to do.As said, to do it legally you could actually in some places become a contractor.