So I finished Dragon Haven (Spoilers)

[Liquid Ice]

I felt the ending was satisfying, but the way Rapskal and Heeby found Tarman was a bit surprising. It seemed almost too convenient.

That actually was the only Robin Hobb book ending that I saw 100% coming. Knew that they'd live to tell the tale and then be flying and finding.
I was a bit disappointed about that actually.

Doesn't it require the ability to use the skill to be able to use the pillars?

Pretty sure so yes. Or at least, I think I remember that the less experienced you are with the skill the worse it's effects are when using those pillars.

So if someone with no skill training was actually able to use a pillar they'd die or become mindless.