Yes it is but id leave it till early spring when you do it . you could of done it late summer ie oct ish . just be carefull and try and do it and keep as much soil as possible . also a lot of acers actualy get quite big so get an overly big pot .

Yes, no probems, and, as Np says, spring time, as they're coming into growth and their new roots are starting to reach out. One word of caution, though. I would tend though to use a pot just big enough to accommodate the roots, or at least one into which they will grow this season. They don't like to be in too large a pot, into which they haven't rooted fully, for the winter. They refer being on the drier side through winter, and if their roots aren't taking up the excess water in the cold weather, they can get watelogged and then damaged by hard frost. I think - better to be prepared to pot on as the years go by. Worthy

Keeping them contained in a pot will also mean they remain small longer.

Be sure to prune the top somewhat the day you dig them up. I would remove all of the little twigs less than 1/2 the thickness of a standard pencil, and generally clean up the structure of the plants at the same time. A mixture of 1 ml each of white vinegar and seaweed extract per liter of water makes a good organic root stimulator.