You don't need a mod chip to play backup games or run any of the momebrew.
1) You'll need a tri-wing screwdriver, they often sell them on modchip sites with your order for an extra fee. You'll also need a small screwdriver for the other screws, the Wii case has a mixture.
2) I have no issues with my Wiiclip fitted Wiikey2, it seems to work just fine. Wherther it'll work with yours, I don't know. Some say you should solder and it is cheaper that way but for ease of use clipping the thing on was jnust too simple.
3) Yes. All chips are safe online, so is softmodding.
4) Burnt DVD, the Wii doesn't do CDs (afaik).
Hope that helps.