Yep, I have the Carrie Hoodie in the thistle heather. It's definitely a greyish purple color. Mine has a charcoal grey stripe and the thistle part is clearly much more purple-y than the stripe. I do think it would go nicely with dark grey or black though. Anything does...those are neutrals!
For washing, I have washed most of my knit Ibex stuff in the washer on gentle (in cold). I make sure not to use fabric softener and I air dry everything. I do use Dryel for wool work wear...particularly jackets or pants that have a lining. It freshens them up nicely and allows you to go much longer between dry cleanings.
I have also found that with the exception of dog hair (a big issue in my life!), my wool items just don't need cleaning as often as other stuff.