A: HI your question is to generic to answer, their is vertical and horizontal , then how is it supported ? I have made a frame out of 2 x 4's and put this on the top then put a turtle tank on it weighing in at 300 pounds, how ever the weight is transferred through the frame to the legs so each leg is supporting 75 lbs with is nothing for a 2 x 4 to hold. long story short, you need proper planning before embarking on any job that is load bearing to the extent that you wonder weather or not the board in question will fail under the weight. Since it is 1 thing to DIY a kitchen table and another to DIY a water bed frame.
A: no 3/4 would be 24/32, so their is 1/32 difference in thickness.
A: I don,t know why not. But I used it for another project.
A: Hi, yes 3/4 or 23/32 is what is required in most places for a sub floor. which one you should be using would be determined by your local building codes.
A: about 30 lbs