Hmmm....have u thought of asking your brother? Since he would be playing.
There's a lot of information on the official WoW website but you'll need to spend a lot of time reading. In fact, if you want to play WoW very well, you have no choice but to read up. Reason is that WoW offers a lot of choices for you to play with that making the wrong choice is bad.
And you can't compare RO with WoW because RO would be more simple than WoW. A hell lot more simpler. Also, the players are much older and very strict with people who annoy them.
Try this site :
http://www.wowwiki.com/Getting_startedHowever, I would suggest you take the next few days just to read up a bit more about the game. Then only ask when you don't understand. It may take you a few times to read it through but that happens to everyone, even to people whose English are good.
If you're just starting the game, you won't be able to raid until you're at least level 60-70. Like I said, read up first.
For speed leveling, can use Jame's Guide.
http://www.wow-pro.com . And a lot of ppl are saying that it's better than those leveling guides that one pays a lot of money more. So use that for leveling.
Also, take your time to level and enjoy the game. And do it on your own. If you get someone else to level for you, you wouldn't know how to play your character. It gets very obvious when you're partying in a group or doing a raid. And people will get very nasty if you don't play your part well.
WoW probably has more adults than other MMORPGs so they expect a lot of common decency and politeness from one another. A warning : Playing with adults is different from playing with kids. Why? Adults will make the effort to get you banned/suspended. Kids can't be bothered.