First off, welcome! I'm by all means not trying to scare you away. Just getting these things flowing through your mind. Theres a lot to do before you can get out and level!

Opening 5 wow windows is one thing, multi-boxing is a whole other thing.
You're still going to have to set up your keyboard broadcasting software, which can be a challenge if you have never done it before.
You're gonna have to make the accounts.. dig deep into those pockets and pay up.. get situated
Figure out what to roll.. Figure out the realm.. The faction.. The races.. Wouldn't want to pick hair you won't like later!
Get the names figured out.. Make them in the right order so they show up in party how you want it.. If you're OCD about things like that, like I am.
Get logged in.. make a few macros to start out.. learn to start controlling them all..
Make macros for party invite.. all-in-one accept macro.. spread out macros.. formations.. things to make you look cool......

And I'm not even to the part where you level them up yet.
Read read read read
If you've read and searched, and still don't have an answer.. that's when you can reach for the new thread button.
I guarantee 99% of your questions have been covered somewhere in these forums. Search is your friend.

Again, Welcome!