White or "natural" is best, so you don't have to be concerned about the dye that makes the colors. I don't bother boiling, as I feel there's so little there... and personally find it's flavor - which goes away very quickly - doesn't bother me. (Conversely, I'm one of those who does taste a flavor in cartos, and it doesn't go away.)
Any thing can be overvaped (hey, I don't care that the spell checker is telling me that's not a word!

It's an evolving language folks!) by chain vaping. But you don't normally need to wait 3 minutes between draws. And running too high a power level will make it worse.
Try fluffing out the yarn where it exits the cap, that may help. If you're getting dry hits, try drawing a little easier. And maybe turn the power down a tad. You can burn cartos, too, and then it's not a question of replacing the wick, but the carto.