I prebait all my cat sets with beaver but usually bait the trap with duck carcass,I like the look of the feathers.
3 Nails I only have 3 sets out I do not set a trap unless a cat has worked a bait,I check my baits about every 7 to 10 days,some get hit right away some take several weeks.
The only advice I have for tracks in the snow is make your set in a creek drainage so you can walk in the water,no tracks in water.