Sealing and insulation are the keys to cold weather comfort, nothing worse than cool drafts, or warming up the great outdoors at minus 30.
I have never seen the expanding foam contract. I like to seal all edges of poly, (particularly to the subfloor), window and door rough framing, and overlaps with acoustic seal. Installing receptacle boxes I wrap them in a 16" square of poly, then pull it through the vapour barrier once in place, then seal it with acoustic seal. If done carefully the structure becomes so tight it’s difficult to slam a door shut, and a wood stove needs a ducted air supply to breathe properly ( probably not a bad practice anyways, as otherwise air will be pulled through every defect in the vapour barrier to supply chimney draft).