1. While i don't advise it and it probably won't do you any good, sure. You can use almost anything as a magickal instrument. But i suggest real wood. (if you need more detail about that, just ask)
2. I am sure plenty of people could give you a summoning ritual. But first i want you to clarify to me and everyone as well as yourself why you want to summon anything, what it is you want to summon, the possible reprocussions, and whether or not you think you are ready. Summoning magick has about a 70% chance of going wrong in some way, minor or major, even with defenses up. :/ Are you sure you are ready to pursue it?
3. You can put absolutely anything you use for magickal purposes, or feel spiritually connected to on your altar.
If you have anymore questions or concerns, just ask :)