The medical delegate is a doctor. The trackside marshals will
not need to apply first aid in most cases (unless the driver
collapses after getting out) - if the driver is unable to get out
of the cockpit, they will need to unlatch the safety cell for
removal when the medical car and ambulance arrive as this prevents
further injury to the spinal cord.
I may be wrong and the organisers may need medics for other
purposes, so keep a lookout for openings.