Is there a difference in quality between cotton/linen and jute and what is the difference?
The substances are both sound and GLASS FIBER.
The jute fabric is structurally coarser, thicker, stugger and can be washed
a few times on 30graden wool was (and is often not necessary, it may well be vacuumcleaned). Cotton/linen can be washed, as often as you want, on 40 degrees in the washing machine, both substances are highly suitable for cats nails.
 
What is the diameter of the pillows?
The top cushions are 50cm diameter and the bottom and middle cushions of the 1,2 and 3 cushion trapeze are 60cm diameter.

I have a lowered ceiling and it seems to me that this is not concrete.  And I have no bars, can I still confirm it to the ceiling,
without the entire ceiling comes down?
There is still a lot of unnoticed weight when my cat is going to swing the trapeze.
In generaly we advise to hang the Trapeze to a decorative hook on the wall, or a hook attached to a concrete ceiling.  A lowered ceiling is mostly of gypsum. We therefore advise you to use a decorative hook.

I was wondering if there is a choice in colors?
There are two substances: Jute (camel-colored) and cotton / linen (ecru / beige color), the latter allows you to use textile paint, so you can paint your Trapeze in the desired color, and reserve, at all times, the selected substance for cats nails.