My welding table top is 30"x56" in size made from 1/2" thick steel. It is fully braced by 2"x6" tubing and the lower shelf is made from 2"x 4" I beam. The scrap yard that I bought the metal from had a track torch and cut the table top with true 90% angles on the corners. This is very helpful when your building corners. I do not have any holes in the top. What I do is mount by bench tools on "C" stock. When I need one I clamp it to the table. I have several tools mounted this way. Vice, shrinker, stretcher, Shear, rebar shear, and a small anvil. All of my clamps are stored on the legs of this table.
I put one the best wheels I could find. This was a mistake. I have 2 straight wheels and 2 swivel wheels, BUT none of them lock! If I bump the table it will roll slowly across the shop. Now I put wood wedges in the wheels.
I have no ideal of the weight but I am not worried about any one stealing it.
Make all of your tables to the same height. That way you can join them together for a long project and it eases sliding heavy items from one table to another.
I hope this helps you some.
