1) Awesome
2) Be careful. You will find many recipies online for homemade chloroform. Do not use any. In these recipies, many other chemicals are made which are HIGHLY cancerous, like, WILL give him cancer. If you want to use it, get it from a chemist and be sure to tell him it will be intended for human purposes (or at least ask him "hypothetically")
3) Nitrous Oxide will not work. Firstly, he would have to be co-operating, because it is not a vapour, it is a gas, and im sure your friend wont let you spray compressed air into his mouth. Besides, he would only stay out for about a minute if he even passed out.
4) If you do find out where to get safe cloroform, tell me.
5) Aweseome...