What are some best practices/protections re cooperation agreements to prevent tenant poaching among multiple residential and commercial developers on one development site?

What recourse do I have against him and is there any language I can add to my lease agreement to prevent this in the future?

To prevent injury, squatters, and theft of any functional appliances or copper pipes, screw plywood over each open window and door.

First it’s something I need to learn anyway so I can generate accurate rehab costs on my projects which will prevent me from getting screwed over by other contractors in the future when I don’t have time to rehab my own houses and secondly I can partner with another investor that has cash and we can split the profits.

That prevents them from just cancelling the check.

I.e. if there were many property losses tied to the carriers property book, the carriers will subsidize the loss leaders with you.I would not advise shopping your insurance every year so as to prevent what we call "market fatigue". 

what galls me though is when landlords in one market (I work in The Dalles, OR) raise rents to another market (Portland, OR, for example).  

also what can we do to prevent this next time, our title company closer said next time we should do an escrow agreement, is there anything else i can do to avoid this in the future ?

These guidelines are set-up to prevent fraud.

That should prevent your tenant's tanks from running dry.I believe Devany Oil serves most of the Boston area.