Well guys, I've followed your advices.

First of all, I restarted the campaign, I had really no hope. I started as you suggested, and I attacked the Aedui in the second turn (the movement restrictions didn't let me attack in the first one) with almost all I had.
With the main army I obliterated an Aedui army with a Heroic Victory, very near their capital (Gallic for Alesia maybe?), so I took it some turns after that.
There were some reinforcements who were suposed to meet the main army, but got attacked in the way, and I kept retiring until I got very near the second transalpine Aedui settlement. I obtained a Heroic Victory against an army of them once again (thanks to the Gallic Light Cavalry... I really like that guys, although as you say, are very expensive to mantain), and then I took that settlement.

BTW, I didn't assaulted the walls... I just let them come out for me... I usually do that... is that completely wrong? I know I lose a lot of time, but it assures me the victory.

I left the Cisalpine Aedui Settlement, so they're still alive, and I don't plan to attack them anytime soon. But even though they have just one settlement, they just don't want to become my protectorate , maybe I'll have to put an army outside their doors.

Now I have a doubt, about the Reforms of the Celts... is the Lv 4 Market the one that costs like 6000 mnai, or one even larger? And will the other Celtic factions help me with that? I mean, I know they build up their cities and everything, but I'm not counting on them

And, what are the units you get in the first reform? Neitos and Arjos?

Thanks a lot again guys