24x24 really isn't a very big work surface.
A vise is going to take up a good portion of it...
A piece of railroad rail or an old anvil (NOT a new cast-steel splinter shedder) would be a good addition to the other part of the table.
As for work height, blacksmiths used to tailor the work height of their anvils so that when their hammer was resting on top of the anvil (at the bottom of their hammer blow), their elbow was at a 90-degree angle. Guys who made a living hammering 12 hours a day quickly figured out what the optimal work surface height was!
For wheels, you could put two heavy-duty casters at the back of the legs, just off the ground, and a handle at the front as you said.
Also, for feet, I'd look at some heavy-duty machine pads. You want something rubber under the legs of your hammering table, or you'll chip up your shop floor.
-Brad