The last one i ordered awhile back was plywood covered with some anti-slip coating.

It is best to use the MultiCart RSD14 Solid Deck for R14, R16, and R18 MultiCarts. https://bhpho.to/2YiIgH2

Yes, you can use the MultiCart 2-Tier Multimedia Shelf Set at the same time as the deck.

No, the tabs won't go under the frame that way. However, if they made it differently it would be possible.

You must first remove the floor in order to fold the cart. However, this is a very fast step. The floor comes in 2 sections and allthough you can attach it to the cart, it is not necessary because gravity, and the weight of your gear, will keep it in place, so removing it is a very simple and fast procedure. You do have to store it somewhere in your vehicle.I also purchased the shelf for my R12. It is a bit more labor intensive to attach and remove the shelf because of the square tubing attached on the bottom, and connecting the 2 sections. I almost always use the cart with both the bottom and the shelf. On the job, I'm a photographer, the shelf becomes a table for a laptop, light meters, accessories, etc. as does the bottom.The cart, equipped with these 2 accessories becomes a very nice, and inexpensive, production cart.It can also be configured with only one section (the slightly longer one) of the floor, and / or the shelf.These 2 accessories fit the R12 and 2 others with different wheels. The R12 has the best wheels, it will go anywhere, but this comes at a price; it's more expensive, and a bit heavier and larger when folded.