You should alway ask about any PPE that you do not know about, ask about how to use specific peices of equipment, ask where the first aid kit is, inquire as to any specific hazards, and what is outlined within the Emergency Response Plan.
In the event of an injury, or an accident, you should report it to the supervisor.
If an employer asks yout to do something that is unsafe, you should contact The Workplace Health and Safety Contact Center.