No offense intended to anyone here but this is an industry full of posers and wanna be's and you as an investor must vette each source to insure it is credible and that cannot be done here.  

I want to make sure that these new "occupants" are not criminals and was thinking about doing the following, please let me know your thoughts/suggestions:1.

He basically just told that Washington state not only made it illegal but criminalized flipping and wholesaling properties and that you needs to be a licensed broker to wholesale houses.

You combine that feel with hard credit & criminal evidence, work ethic, and you will usually make good choices. 

You will also want to pull credit and background check (although you can't "blanket discriminate" against someone with a criminal history).(3) This is a very smart question to ask ... and yes, you want to change it over to a summer turnover.

I do have neighbor complaints and the police have been there although no criminal charges.This is a relative to make matters worse.

I also have a terrible roofer, and an HVAC guy who borders on criminally negligent.

The civil penalty shall be no less than $500 and no more than $5,000 for each offense.

Start out with the traditional criteria (3X rent for income, good credit, no criminal record) and go from there.

There is something about being in a 8'x 8' room for 8-10 hours a day that made me feel like I was slowly dying or that I was a criminal (at least my cell had windows).