So you should define what a "STOCK" Brompton is in your opinion... The space for tires has only changed very slightly over time but this may offer a more convenient fit for the Scorcher. It will fit even on an MK2 as far as I can judge but there's no guarantee. You might geht into trouble if your Brompton has mudguards - it might be an easier or harder fit and it will be tight anyway. So: does a "STOCK" Brompton have mudguards?
Depends. Again: In Brompton size there is currently no wider tire than the 40mm Scorcher so even if newer models would offer more space it would not make a difference.
Apart from that: Which problem are you trying to solve? If you want a folder with the widest tire possible (just because you like wide tires) than the Brompton is not for you. If you want to solve a different problem it would probably good to name it instead of "wide tires".