5/8" to 3/4" Put the screw in bracket and hold up to edge of plank. You'll see which one will not allow tip to go through board. If you want nice wood, use the more expensive "Clear Pine". More expensive but better quality. Available at HD.
Hi, yes they can be glued together as that is how they make plywood. I would also screw them together as well.
Yes but you need to make a box with sides on all four sides and a center support in the middle to keep it from caving in when you walk on it. Or make a box as above and use a piece of exterior plywood like a half sheet handy panel. That would be a little stronger.
Yes they work great
Yes you can get them in4-6-8-10-12-14-16 foot boards
No they really need to be double the thickness
many times less than .75in
I would not trust them
Yes. And upload all the videos of the ambulances rolling in
Saw dust when cutting or sanding.