Is this cart also have a height-adjustable top shelf?

The top shelf of the Victor Lite cart is Fixed.

What are the differences between victor lite and v1.1?

The main differences between Victor 1.1 cart and the Victor lite cart are the following:Top Shelf: Victor 1.1 cart has up r_3QW$g,SB5Is)aamp; down movable top shelfand the top shelf of the Victor lite cart is fixed.Cheese plate: The Victor 1.1 cart has an In-Built cheese plate on the Top Shelf whereas the Victor lite cart has no cheese plate in-built.Locking Mechanism: Both carts have different locking mechanisms.Wheels: Victor 1.1 cart has 9" Pneumatic wheels.whereas the Victor lite cart has 10" Pneumatic wheels.Shelf width: the shelves of Victor Lite carts are wider than V1.1 modelthe tray/shelf width of the Victor Lite cart is 27.5 inchesbut the width of the V1.1 cart is 24 inches

As far as the payload the lite is 200kg total between top and bottom? Meaning 100kg top shelf and 100 bottom? Is it because the shelves are heavier and more solid? Could they be swapped with stronger ones?

Yes, the total payload capacity of Victor Lite Cart is 200kg, The top shelf load capacity is 100kg and the bottom shelf load capacity is 100kg. And the shelf cannot be swapped as the top and bottom shelf of Victor Lite Cart are fixed.

What carpet you use for the carts ?

The Black non woven carpets are used on our Carts.

Do you make a cross bar that fits the inside legs of the Victor Lite? this cross bar only fits the outside legs.

Swap the clamp inside which makes the length of the crossbar equal to the length of the narrower side of the Victor Lite cart.

Is it possible to attach a middle shelf?

Yes, it is possible to attach middle shelf in Victor Lite Cart. We are selling Center Shelf in five sizes (32", 36", 38", 42" and 48"). It is compatible with our other carts (Victor V1, Victor Pro, Victor Lite, Atlas V2 Bowado Pro Camera Production Cart) as well.