My pumpkin stalk has snapped - though still leaving a good 4 inches attached to the pumpkin. I'd read that it was best to leave it attached for as long as possible, will this have any negative effects?
They can start rotting outside, fungus, etc. They don't do this in their native warm climate. I suppose it's alright to try leaving it outside, but I'd be minded to cut the stem short and put it in a cool dry place outside to see if it will fully ripen there without starting to mold over.
I would say not cool and dry - general advice is to ripen at 20 - 25 C after harvest for 10 days, and only then to store cool (10-15 C). Should be fine though, definitely getting to time to harvest anyway (we currently have squashes sitting on most spare surfaces in the house )