It's not all that different from styrene. The biggest difference is that little resin parts are brittle and break easily. Also it can't be assembled with solvents, like styrene can.
I guess the right term would be the "pouring block".
The best way to remove parts is with a saw, leaving some of the block on the part. Putting any stress on the part as a pressure slice with a razor blade or cutters would may snap it at it's weakest point.
Resin sands easily, so once the part is free, hold it firmly and rub it on sandpaper taped to a flat surface to remove the rest of the block. Sometimes this is quick, sometimes it requires removal of a lot of resin.
Resin dust is bad to breathe. For an operation as described above, just be careful to sweep up the dust and dispose. But if you are using a belt sander or a Dremel, wear a dust mask.
It glues to itself with epoxy, but it glues to both itself and styrene with CA, so that's the best adhesive.
One of my favorite things about resin is that a good source can make a piece that equals the detail of an assembly of a dozen parts in styrene.
I hope that's helpful,
Bill