Cottonwood pass has better access than Independence pass My experience of Indy pass is tons of avalanche paths with a relatively small amount of rideable area. The pass over cottonwood is groomed at least 2x a week so getting to the goods up there is much easier. The only problem with the wood is all the sledneckers that get up there and track much of it out (only on the weekends is this a issue). I hope that this helps you out. As far as time from BV the trailhead at Denny Creek is about 15 min from town and another 15 min on a sled will get you to the top-o-the pass and the goods. Last year I lived at Cottonwood Hot Springs so it was less than 10 min to the trailhead.
If you go up to Cottonwood Pass it is great to hit the springs 10 min after the end of the day.
As far as I think that is middle cottonwood creek I have paddled some just above the Denny Creek trailhead and it is a very short 3+ log chocked section followed by a gorge that may be marginally runable 5++, if someone got in there and cut out the 100 or so logs jamming it up way to much work for me maybe someday I will get enough time to get in there and try to clean it up a couple of guys could do it in a weekend.