1) I've skied the Sherburne and GoS trails in January, but not up on the steeps. You really need to have avalanche training to go up there at that time of year safely.
2) Again, it can be wonderful on occasion. It's also very often icy, crusty, and potentially deadly. You'll need to have full avy gear (probe, beacon, shovel, training) plus crampons, ice axe, and self-arrest training. Mid-winter skiing is not to be taken lightly. Others have reported great snow at times, so it can be rewarding, but only for the prepared.
3) There's aren't any real guides to the terrain on the west side of the mountain. The Goodman book has some basic info. It's best to go with someone who knows the area and learn that way.
4) There's no average time, it varies a lot. It's much quicker up from Tuckerman then from Ammonoosuc even though you start higher on the west side. The Ammonoosuc Ravine trail is steep and narrow; the Tuckerman Ravine trail is a road. You can make it to the Ravine in 2 hours, expect at least that to reach Lakes of the Clouds, much more if you have to break trail.
5) Spend some time on
Time For Tuckerman and you'll find lots of folks who go up there on a regular basis.
5 hours from the trailhead to the top of the ravine is awfully slow. If you do it more often you might learn how to cut weight, speed up the pace, and enjoy it more. There's lots of great skiing up there that you haven't yet experienced. Without experience in the real backcountry (Tucks isn't really backcountry) I'd be reluctant to suggest trying some of the stuff on the west side of the hill.
There's still skiing this season; are you sure you're done for the year?