The trails are burried under about 6 inches of hard snow, snowshoes are not required for anyone under 150lbs (with bab included). Marcy Dam is NOT safe to go walking on as the recent warm spell of temperatures has melted a good deal of the surface ice (and there is evidence of someone falling in torwards the west-side lean-to).
The trail up Phelps is covered in as much snow as the rest of the trail, but mostly resembles a hill-and-dale trail with constant ups and downs. If there were any boulders on the trail that posed a problem, they are burried also. During the assent, there are 3 spots that require special care going up and down. Sticking torward the treeline is reccomended. Ice Gear is not required, but would make it easier.
I would say to dedicate 2 hours to climbing this trail from the VanHovenberg trail. The icy parts will take 15 minutes each.