I often enjoyed playing Risk with my friends, but some of the rules weren't so clear, and we just settled an agreement between us. Note that I'm talking about the "basic" version.

1) Does the game end...
a) as soon as a player reaches his goal [like we mean], or b) at the beginning of his next turn [as some friends of mine think]?
If your goal is to destroy an opponent's army, that's quite obvious; but if you have to conquer 24 territories and you succeed, you could not have all of them at the beginning of your next turn. I think that assuming that the right rule is b) would lead to a disparity between Goals, as in the example.

2) When you are launching an attack to a next territory and the opponent has the same number of armies as the attacker, can the attacker use all of the armies?
We say NO, because if you attack with three against three, or 2 vs 2, you could lose all of your armies with that attack, so you'd leave your territory with no armies, and you can't. So if you got 3 and the opponent 3, you can attack with just 2. But if, for example, you win, you now got 3 and the opponent 1, and you can use 3 armies to carry on the attack because even if you lose this time you keep at least 2.

3) When things get bigger, and you are attacking with something like 15 vs 5, the battle's initially carried with no more than 3 on each side, that's right. But if you win the combat, dice after dice, how many armies you move in the territory you just got?
Some say, all those you used for attacking
Some say, no more than X or no less than Y...
We always did like this: when you conquer a territory, you can put there as many armies as you wish from the attacking territory, as long as there's at least 1 in the old and 1 in the new.
Restricting the number of the armies you can move would make the game awwwwwfully sloooow.

4) at the end of your turn, when you've carried out all the combats, you can move your armies.
As many as you wish?
From where you wish?
To where you wish?
How far you wish?
This was the most controversial point, and it's important, especially when dealing with many armies.
We did like this:
Choose just ONE of your territories
Take as many armies as you wish from there, providing you leave at least 1
Put ALL OF THEM TOGETHER (no split) in JUST ONE of the adjacent territories.
Stop. So, it's just one move. You can't fly your troops straight from Japan to Africa, you can't say "ok boys, stand up, and some of you go north and some south", and you can't say "you in Brazil go north and you in England go east".

Everything's OK when you agree, but what are the official rules? (don't know about Tournament rules, but I think they're a totally different set of rules)