There's a lot of good stuff in this thread by Devil505 Shaking Down/Reloading A Mature Fire
It should help answer your current question about the fire.
I have the newest model that does not have a hopper insert. For the hoper inserts, I don't have anything to offer from first hand experience. From other operators that I knew who had the '80 vintage units, it was most important to keep the hopper parts sealed when installed. If the draft leaked from somewhere in the hopper installation, it will not be pulling air thru the fire where it's needed. When they leaked they always had trouble keeping a hot coal fire, even with a chimney with great draft.
Maybe others know, can the hoper component joints be sealed with furnace cement?
Regarding stove top temperatures, my model's operator's manual states operating temperatures of 600- 700. My Vigilant II has the fire directly beneath the ground cast iron top loading door and coal burns roughly~ 2,000 F. I regularly burn in the 600-700f stove top temperature zone during the main part of winter and have been for seven seasons. Many stoves are convection or forced air units and therefore have air moving the temperature out from between a space between the fire box and the exterior of the stove. Stove top temperatures would be lower in this style stove. Vigilants, all models I believe, are designed as radiant stoves. No blowers, just radiating heat from the surface. The exterior sides and back of the stove are not part of the firebox. They're the outside of the exhaust chambers when the internal damper is closed. On my model, the top and the front doors are part of the fire box and are exposed to the direct radiant heat of the burning coal. I measure stack skin temperature of = 250F at 6', stove top of 600-700 and the stove's sides measure ~4-500F. I use an IR thermometer as I've found that the three magnetic surface thermometers I've owned to be way off, as much as 25%. That's even when they calibrate at ~210 when suspended in boiling water.
It will throw heat. It is rated at 50,000 BTU, not as large of an output as other coal stoves. I run mine well under 50,000 btu/hr unless it's near the single digits. Then I operate it at max and put about 85-90 Lbs of pea thru it daily. I keeps my 10 yr old 3,100 sq. ft. home comfortable. The extremities of the house when it's really cold will be in the lower 60s. The oil hot air furnace will only run when the temps are single digit with the thermostat set at 68.