It looks like the Crown can still request Replacements during the Winter Turn Supply Phase; it only looks like it is prohibited to place them. Assuming this is correct, it is possible to have two unresolved Replacement chits in Nova Scotia at the start of the Supply Phase on the Turn following a Winter Turn.
1. Can both of these chits be removed from Nova Scotia during the same Supply Phase and all of those replacement units be placed in Nova Scotia?
Yes, they can. I've done it before when playing the Crown side myself, but it's usually (though not always) sub-optimal; that is, there are certain situations where it makes sense to do so, and lot of situations where it doesn't, IMHO.