Medical payments coverage is triggered by "bodily injury," subject to the definition in the policy. It is paid without regard to negligence, and is usually seen as a means of avoiding larger liability suits. See CGL technical report Medical Payments--Automatic?
The term "accident" eliminates medical payments coverage for intentional injury by an insured, but intentional injury by others on the insured's premises would be covered.
Notice that the accident must arise out of the insured's auto dealer operations, defined as locations used for an auto dealership and operations necessary or incidental to a dealership. Accidents involving autos are excluded by virtue of the Auto exclusion in the General Liability section, which is incorporated into the Medical Payments exclusions.
Although the accident must occur during the policy period, the expenses can be turned in (incurred and reported) within one year after the date of the accident, even if the policy has expired.
The expenses payable under medical payments coverage are specified in the insuring agreement. "First aid" usually involves the insured's out-of-pocket expenses for rendering aid at the time of the accident, including emergency transportation to a medical facility.
There is a separate limit of insurance for Coverage C - see F. Limits of Insurance – General Liability Coverages.
Endorsement CA 25 52 (Exclusion - Locations and Operations Medical Payments) eliminates this coverage.