1) Don't get slotted, other than that, ATE premium one's are very good discs with an unbeatable warranty.
2) Pads are okay, but not the best.
3) You don't need this. Just more work/brake bleeding
4) Doesn't matter, as long as it meets OE spec.
That said, I would suggest you just get Brembo discs, and Textar/Pagid/Jurid pads.
Nothing beats OE pads in terms of braking, but yes there will be plenty of brake dust.
Stay far far away from any slotted or cross drilled rotors. There are purely for looks, and your car will actually brake worse.