I had one. The HIDA/CCK is a diagnostic test, so it's not going to cure anything. That said...
1) The first portion of the test was only uncomfortable because I was laying on a flat metal table for an hour without moving. I really, really wish I could've had my iPod.
The second portion of the test, when they inject you with the CCK, THAT part was annoying: lots of bloating, a bit of pain, and LOTS of nausea for about 5 minutes. Your symptoms here may (and probably will) differ.
2) Test outcome: Ejection Fraction (EF) of 19%. A normal gallbladder empties at a rate of somewhere between 40% and 75% (with 35% being the point at which they start recommending removal). Explained part of my problems.
3) Somewhat. While I haven't gotten my gallbladder removed, I have learned to eat better and have lost a ton of weight. Still, I'm considering getting it removed, as per the doc's recommendations, for a number of reasons.