Not all fire extinguishers will put out all fires. You must check your fire extinguisher to make sure that is equipped for all fires since different fires must be put out different ways.
Carbon dioxide is compressed under high pressure inside a CO2 extinguisher.
Depends upon what sort of fire extinguishers they are and where they are installed.
For instance, a commercial cooking fire extinguisher must be inspected every 6 months and should have certain types of maintenance done during each inspection, according to NFPA 1 Fire Code. Different code may apply in other jurisdictions.
Also, portable fire extinguishers may need to be examined on a monthly basis, and records kept; some types require annual maintenance; others require maintenance at longer intervals (e.g., 5 years or 12 years).
Stand 8-10 feet away from the fire