With regard to setup and sound, Chris said it very well:
Originally Posted by Chris Fitzgerald
It's kind of hard to separate the two. Because our instrument is an acoustic one, every change in setup affects the sound.
You'll find quite a bit of variance among players with regard to their setups. For example, my string heights are much like Chris's but, depending on the player, the bass, the strings, etc., string heights are quite variable. As for the finicky part, you'll notice that many of us have bridge adjusters. For me and many other players, they're there, not because we're often changing heights, but because adjusters allow us to dial right in to the "sweet spot."
I've found, and I'm sure others have as well that, across seasonal changes, a very small tweak of the adjusters makes a substantially bigger difference in "feel" than would seem to make sense from the sub-millimeter change in string-height that it causes. Across seasons, these small adjustments seem to be compensating for changes that occur in the wood of a bass with a carved top. The changes re-adjust the force on the top. Bottom line: Finicky? Hell, yes!
Then there are instrument preferences including neck profile, shoulder slope, fingerboard overstand, fingerboard radius, and on and on and on...