Advice on managing out of state rehab

Hi all,

I'm curious to get everyone's lessons learned / best practices regarding managing out-of-state rehabs. To start....

- How are you allowing contractors in/out of the property & securing materials?
- Do you have them buy the materials? Do you typically pay 50% upfront? 
My concern here is having materials getting stolen & or a contractor taking 50% and walking.
- How are you keeping up on their progress?
My hope is they would provide weekly updates with pictures, but I'm curious on how everyone else gets updates. 

Thanks,
SL