Mine's dark grey. Certainly wouldn't paint it. I think paint would negatively affect how it functions.
I suppose you could, but honestly I don't think it's worth the trouble. Deer see movement more than anything else, a light color in the tree canopy is common place. Personally, I wouldn't worry about it in the least.
They sell it in most every laundry section of any grocery store or Wal-mart. Should be pretty easy to find. I have used it for dying raffia grass for waterfowl blinds. It works well. Just don't get it on your clothes or anything else that you value.