Id have to agree with IronHawk on some points.
I dont particularly like CBM but many find it an interesting variation on the game. There are also other mods which can change the games play quite abit. But the vanilla game is also fantastic. It can take up to a year to play all of the features of the game and get tired of it. Then you can decide what variations you would like to try.
As to "most MP games are using this mod" that isnt true. Altho most of the games in the IRC chat room seem to. But in general, in the mp forum, on LLama's server, and on my server it doesnt seem to be. However most of the games do seem to like the Banners, and the Worthy Heroes mods.
A couple of hints I would give:
1) The nations are all fairly unique. They each have strong and weak points. Also this game is not 1-on-1 balanced. Its more rock-paper-scissors. So dont be quick to tell us that a particular nation is unbalanced by being too strong or too weak. Chances are that later you will come back and say that you have discovered that nations particular ability vs another nation. Also what seems strong/weak has alot to do with your playing style. Try them all and find the nation that fits your style. Armored? Research? Defensive? Stealth? Barbarian Horde? When you finally decide what nations are strong and weak, dont announce it because yours arent going to match other peoples.
2) If you find your games too hard to win in the beginning then there are two things which can help slow down the AI. Make the maps abit larger. And set the independents to a higher setting. For some reason new players always feel that setting the indepts weaker will make the game easier. You can make smarter decisions about attacking independents than the AI can. Setting the independents stronger helps to keep the AI from swarming you early in the game.
Gandalf Parker