Yes, it is a quarter repeater in an 18K case, the case alone (with crystal only) having 80,0 g. Yes, with a fusee, of course. "Bull´s eye" crystals were rather rarely fitted to top grade watches in that era originally.
Regarding the escapement, it has a cylinder escapement and this seems very unusual at the time to be combined with a free sprung (early) Pennington compensation balance. This was what caught my attention initially. Close inspection of the movement then revealed that it either initially was a detent chronometer, or that the raw movement was designed to be fitted with both kinds of escapements as alternatives. The only tell tale is that holes for steady pins and a fixing screw for a detent foot are provided. The cylinder escape wheel is placed exactly where the detent escape wheel would have been. But there are speculations possible only. At that time English cylinder escapements were highly regarded (and very fine executed). And a customer might have chosen to prefer a cylinder escapement due to the fact that this is self starting, whereas a detent escapement is not, and even may stop running occassionally upon a "matching" movement of the watch (in most cases rotation around an axis of the balance). Insofar the cylinder escapement is the more practical escapement. On the other hand, the locating pins of a detent would have been placed in the plate
after having made the detent. This would point to a later conversion. But if the detent was broken, it is rather unlikely that the customer, who had the money for such an expensive case, would not have the funds for having a new detent being made. But perhaps the customer had made the experience that the detent escapement occasionally stops, and upon needing to have the detent repaired chose the conversion to cylinder escapement for the above reasons.
Here you see the rods and the hammers. And the place where a detent was located or initially intended (whatever hypothesis you prefer).