Wow ok, well lets get started then I only started a couple of weeks ago as well but have found it pretty easy to get going so I will point you towards a lot of the resources I used to get started.

1) Here is a good start, read the wiki, when you dont understand a term go look it up.

2) Besides the programs, macros and addons? really only practice.

3) I had keyclone recommended to me and after setting it up and using it I will recommend it to pretty much anyone. Its only $20 per computer and thats a one off fee. http://www.solidice.com/keyclone/ Other people will no doubt recommend IS, I havnt used it but I hear it is really good as well.
Here are the 2 videos I used to help me get keyclone setup
http://www.wowmultivids.com/tag/how-to-setup-keyclone/

4) Umm I dont know if there is a vital key. But get used to using a lot, I use all my numbers, F keys, arrows, WASD and I will be adding in more (Such as numpad) in the future. Not sure if that is what you meant though.
If you want to know what is key for multiboxers then.... well understanding of how everything is working.

5) If you havnt done the above steps then I suggest logging them out

6) This really depends on your setup. But targetting macros are pretty important.

7) The forums are full of it, so is the wiki(http://www.dual-boxing.com/wiki/index.php/Main_Page). To get started it would be easiest to do 5 of the same class and make them ranged (Hunters are where I started, shamans are popular), just until you get the hang of things. Im looking to moved to a bit of a mixed team for dungeons soon but I understand the learning curve on that is going to be pretty steep so best to start slow.