I prefer vacant since I operate in a pro tenant environment and evicting is extremely difficult.

In a rising interest rate environment, I would prefer to lock in for 30 years on a buy and hold.  

You make it up in 3 ways 1) The government is loaning money at very low interest rates 2) The property appreciates in value because rents go up 3) The mortgage gets paid down while you own it (if your loan is not interest only)All of this works very well in today's environment but just be careful you're not holding one of these properties when interest rates are 10%, rents and occupancy are dropping and your note is called.But if your investment horizon in the PPM is 3-5 years what could go wrong?

In this environment of ultra low rates that continue going lower, such refinancing strategy using ARMs would help increase cash flow, right? 

Maybe it'll help vet them and attract responsible tenants who will take care of their personal environment better. 

In todays environment, selling is the easy part. 

Talk to them about your desired areas and costs and see if they even lend in that type of environment.

Because: -have someone else pay your rent and then some-build equity which you do whatever with since it's your primary residence (line of credit or cash when you sell)-this would be a very forgiving environment to develop your processes for rental management.Finally, partnerships are tricky.

that would definitely violate housekeeping and maintaining a healthy environment.  

My manager fits well and creates a good environment that keeps our turnover low.