Dyes question
Just the one you dyed. However, if you transmute that armor appearance onto a new suit of armor, it will keep the same dye combo you used on the original armor.
using unlocked dyes is free, you can change them whenever you want without cost. (The only cost is when/if you buy a color on the TP)
The colors you apply remain until you choose another color, even if you change armor.
Yes, but it will look like the same starting piece of armor too, won’kitten
The starting dye set is well nigh irrelevant. While it should apply that as a base to any neutral-colored items you pick up, the arrangement of dye channels may vary. Also, if you have three channels on a starter item, and get a four-channel piece of gear, you’ll have a pale muddy brown in that fourth channel until you apply it.
As you can change dyes at will and whim for free (once you have learned a dye, there’s no charge to use it) any time you want to pull up your hero panel for the purpose, you’re really not locked in no matter what you pick at the start.