I got my first JEM today!
I'm with glen on this.
As regards the springs I've tried both formations and didn't notice any difference at all, I just prefer the more unform 3 in a row format ( it's a psycological thing )
The wet and dry suggestion sounds pretty ill advised to me, for exactly the reasons stated.
And lastly, again, any guitar will show frets coming up.
Think of a suspsension bridge...it expands in the heat and shrinks in the cold ( an extreme example I know ) but this is how wood reacts too, it's not a major issue until it affects playability and I'm sure it won't do that for many years, and when it eventually does go the whole hog and get a refret.
You have a fine axe there and with a little breaking in of the springs you'll be right on track in no time.