Will do.
Some questions:
-Is there any advantages to not having a mirage evolve?
-Is there a particular mirage that I need to get?
-anything else that I need to know to make my life easier?
-How is the music?
-IIRC, you gain extra abilities for maxing out mirage's skill trees, and even more if you evolve them and max those out too. Pretty sure you can flip back and forth between any unlocked evolutions too, so go for it. I went for the Platinum, which required looooooots of evolutions. Generally, I preferred evolving one critter into all of its possible evolutions over catching their distinct forms separately. One critter with all three (or however many) of its evolutions unlocked and maxed is stronger than having the three separate evolutions as their own critters. You MAY occasionally need to capture a more evolved form in order to actually open up the weaker form's locked evolution node, but once I was able to evolve the weaker one, I dismissed the redundant capture.
-Nah. Pokemon this is not. Again, I got 'em all. But you'll probably want to keep your teams fluid in order to exploit elemental weaknesses and whatnot. Keep that in mind when you start exploring locations that skew heavily towards mobs composed of the same elements. The game is PISS easy, leveling comes quickly (including catching up new recruits), and it's not difficult to brute force your way through all but the optional super bosses.
-Music is fantastic if you love classic FF tunes. The option wasn't available by the time I got the Platinum, but I believe you can now have the game queue up a random battle theme from all the ones you've unlocked. I recommend turning that on and enjoying the nostalgia. Music's almost as amazing as that Wii Chocobo Mystery Dungeon game.