Here's a website where you can probably find your answers.

http://www.worksafebc.com/insurance/need_coverage/

You will have to check with your local building department for the code.A lot easier to make a phone call than waiting for answers on an internet forum that may be incorrect for your area.

In my area I pay workmans comp for all employees no matter if the job is time and material or bid.That has nothing to do with where you are located.

This isn't your only problem when providing materials. Suppose there's a warranty call. Don't be surprised if your contractor says "You provided it, it's your problem. I warned you this could happen."