The gondola runs all year but closes for bikes on the 14th September (and tradition dictates that it will rain for the entire day)
Fort William itself is a hole, the town planners are all deranged. It does have a lot of accomodation options but a lot of them are out on the south side of the town so not the quickest to get to Nevis Range if that’s your thing. If you’re not hung up on being in a town, Spean Bridge is actually closer to Nevis Range than most of Fort Willam and quicker to drive between… It’s a lot smaller, but nicer imo. But not ideal for food, going out etc unless you want to drive.
I’ve stayed recently at Achnabobane Farmhouse, which is nice- run by a lovely retired couple and their yappy dogs. Has a nice feeling of being away from everything but is actually 2 minutes from the road, and probably the closest accomodation to nevis range. They seem to like groups… The Braes at Spean Bridge is also really good- bit more modern.
I think the nearest wigwam place is down towards Oban. But there’s some at Kinlochleven which is actually pretty close to Fort William, and an ace drive along the lochside. And has brilliant riding of its own- better than anything at Nevis IMO but no chairlift 😉 There’s camping and caravans and maybe a yurt place near fort william