There is no exact answer to how many passengers are served per trolley as it will depend on each airlines style and menu concept.
As a guide about 30 large trays are in each trolley or 45 medium trays or 60 small trays for economy. Tray size will depend on meal type, length of flight and airline. Some airlines have 2 per trolley others just 1.
For Club or First it will depend on number of seats in the cabin as each service may involve more than 1 tray.
Galleys will depend on the airline spec and will be different for each aircraft type (eg. BA will be very different to Easyjet for the same aircraft type and a BA B747 very different to a BA A320)
H