its not really difficult to use 2 stands or more but you have to mess about a bit to get the tension
no there isn't a way to know tension in advance with texere. Give them a call, maybe? Or order one of their catalogues (around £10). Or go see them at the knitting and stitching show id you are in London! (good bargains on rowan too, now i think of it)
food dye colouring is easy. Big pan of boiling water (enough to submerge dye) , vinegar (around 2 cupfuls to be cautious, white vinegar better but doesn't matter overmuch) and supercook dye of your choice. Boil til the water is clear (or vinegar coloured, if you're using malt. Will take around 10 minutes. Then let the pan cool, and then gently wash the wool using lukewarm/cold water (avoid any sudden temeperature changes, this can cause wool to felt). Hang wool up to dry, et voila!
Will work on animal fibres (wool, alpaca etc) and also nylon. The shade you'll get will depend on the fibres-I have got some very nice results by stranding several fibres then dying all together.
The dye is as colourfast as they come. I've dyed wool for kids clothes this way and its fine on a wool wash. If you boil-dye the wool like this, it won't streak but will dye evenly.
Oh, you'll need to know how to wind a skein, really. Do you know this? Can talk you through it.