Finally found my 1st 100% IV Pokemon...

No you shouldn't, and yes I have.

EDIT: Sorry I thought you asked about powering it up. Sure you can evolve it for XP and maybe sometimes use it for training, not worth powering up though.

1. What Zureiyaa said. Evolve it and keep it as a trophy piece. I put an "*" at the beginning of my 100% IV 'mons so that when I sort by name they are at the top. It's fun to try for these.
2. Yes. Most of mine have come from eggs, but I've caught a handful. If you want more get those incubators and walk a LOT.

Good luck!

Caught a wild Electabuzz with perfect IV's and in theory best defense moveset, so ya, probs going to keep and maybe power up for defense when I'm higher level.

I caught a few perfect IV pokemon (Dratini, Growlithe, Staryu, Ponyta). Also got some from eggs (Magnemite, 2 Magikarp, Caterpie). I would keep of them, they are like trophies.

I caught a nidorina 100% perfect ivs evolved it and it got a shit moveset.....