DUNLOPDUNLOP Flying Dee - Protective Footwear Unisex Calf Length PVC Short Wellington Boots, 100% Waterproof and Chemical Resistant

What are they like when its icy on the ground? Is the grip still good?

Using the size guide I was recommended an 11 (my usual size) but these feel really loose. Still pretty loose wearing two pairs of socks. That normal?

I'm 11.5, I'll wear socks. Should I go for 11 or 12?