Hi! Yes, Bowmonts are white. Never had any problems with hardiness, they are good outside. I've never kept mine in unless lambing. We are about 700ft high here.
Foot problems, no different to any of my other sheep. I have heard that sheep with white hooves are prone to foot problems, but I can honestly say I've not noticed this with mine.
I've crossbred my Bowmonts with Dorsets, my friend Max has crossed them with Hebrideans, Lleyns and Greyfaced Dartmoor and all the lambs have been white - even the ones crossed with the very black Hebrideans!