I have got Mettler cotton as well. That cotton embroidery thread has been around since the early 60s (at least I bought some then). Madeira does a cotton thread called Cotona, in several thicknesses (30, 50 and 80) for embroidery and bobbin lace making in a range of 35 colours. If it's only the matt look you're after: I bought two of the Pfaff Hummel kits and they come with a Mettler matt yarn that looks exactly like cotton but actually is a polyester.
I have embroidery cotton thread from Mettler. It is cotton and used for heirloom stitching.I don't see any reason why you can't use your normal embroidery thread for the cross stitch.
You can, but the design info says that if you use cotton thread you will achieve a more hand made looking finish. I was just wondering :) Thank you for you help Ricky