Another one with almost everything still here at our joint home, over 8 months post BD and separation. I boxed up the clothes he had in our dresser to make room for myself, and when he finally did take those, he left OTHER things from his car to take their place. He might as well have peed in the corner to mark his territory!
Also secretive about the OW (until I outed them to family and friends, which sent him into a downward spiral), acquaintances still thing we're a happy couple, and he insists "it's not about the OW", not my fault either, but about him needing to be who he was "meant to be".
Fornow, I think though obviously these generalities hold up for each of us, most of the questions you have fall into the "each case is different" area and can only be answered by time. It does sound like the OW is a bandaid that's lifestyle oriented, and probably not, just by observation, something that one would predict to be permanent. Just like with fancy handbags, other people's husbands that are snagged for status are quickly replaced by next season's model.