1. I think Mt. Rose is dope for a pow day, but you have to time it perfectly. Since you're going mid-December, Rose might be a good bet, becasue it is the highest resort in the Tahoe area. Squaw is also insane on a pow day, as is Alpine Meadows. Northstar if you know where to go.
2. Northstar/Squaw are very far from Heavenly. The 89 is closed in the winter, which kills the direct route to Heavenly. You have to go north around the lake and down the east side.
3. Northstar to stateline isn't very far. Take the 267 to the lake, turn left when it ends, and keep going until you see a "Welcome to Nevada" sign. Some small casinos are right at the stateline.
4. Stay in Truckee. IMO, a good base to get around Tahoe.
5. All I know in terms of packages is that Northstar does 4-pak tickets. That'se the resort I ride at, so I don't know too much about anywhere else.
Hope that helps.