I started working at 14 (in Ontario). For my first job:
No, there is a "student wage" that is less than minimum wage
EI yes, CPP no
No
Only if there are promotions available at the part-time level (my "promotion" increased my pay by $0.50)
After 2 years of working there, I got a $0.05 raise. Yes, 5 cents. The biggest increase in my pay came when the minimum wage was increased in Ontario, which also increased the student wage.