I'm just getting my foot in the door with camps, so I probably will not be much help.
Basic certificates you need are: First aid/CPR, H2S Alive, and PST/CSTS (petroleum/construction safety).
I believe most companies will help you get these, but it helps speed things up if you have them already. Other certificates like TDG/WHIMS etc the company will help you get (from my experience anyway).
http://www.acsa-safety.org/ and Enform.ca are one of the many sites where you can do some online if you want to get some on your resume.
Like most jobs, knowing someone or applying in person, will yield quicker/better results then emailing/faxing your resume.
Drug and alcohol testing and a fitness test are pretty common. My fitness test wasn't anything special: blood pressure/ heart rate, lung capacity, hearing test, bend and twist a bunch of different ways, eye sight, bit of medical history questions, 10 push ups and sit ups.
Any specific questions you wanted answered?
Are you looking to move to Alberta or do the Alberta shuffle (fly back and forth)?