All over the streets you see various business models with regards to street food in Bangkok. This is clearly the upper end of the models with seats, people doing the dishes (behind) and more than 2 staff members. They start at about 6 pounding the paste and cooking in preparation for the day ahead.
The charcoal goes on a ‘tray’ just above the air hole (in picture) and the hole is used to fan the fire or just provide oxygen. If wood is used they put the wood in the hole and burn from there.