1) I have given you the answer the lead designer of the game gave to us in the Swedish section. If you want to do it another way, good for you. But remember that the Berserk doesn't give you any free attacks or anything like that. It allows you to recover attribute points "When you are Broken" but also forces you, when you use the talent, to attack the nearest opponent in close combat (you are berserk after all). If we look at the orcs Unbreakable talent, it also say "When you are broken". Neither of the two talents specify when you use them, only that you can only use them when you are broken but you get the effect immediately when you use the talents. If you go down (i.e. become broken) and you have already used your two actions, you can't do anything (neither talents give extra actions, remember). That is the reason you use those two talents on your next turn (or on any turn that you are broken, really), so you have two fresh actions. Hey, you can even wait two minutes and then use it, if you still are broken by then. But if you want to use it at the instant when you go down, even though you perhaps don't have any actions left, good for you, give the enemy a chance
About being broken. You can be broken in a lot of different ways (well, four). One example:
STRENGTH: You're knocked senseless. <> If you're not dead, you can only crawl and mumble <>
When I read that, you are prone. But if you have another interpretation of it, use that.
When I said it was worded badly, it is the word "immediately". It means that you recover points immediately when you use the talent. It doesn't mean that the only time you can use the talent is when you become broken. Most often it is actually bad to do it then. It is usually better to wait for a new turn (unless your character have not done anything in the turn yet).
2) It happens (a lot actually) when using Hidden Combos, that one or more actions can't be used. In our group, we use the Shove actions a lot just to trip someone so he can't use his next action (since you can't change your card and if you next action is attack, you're screwed).
If you are grappled during Hidden Combo combat, both you and the grappler are prone (without weapons). This stops Hidden Combos (normally), but if any of the two combatants have used the Await action, they have actions left this round. Regardless, the next round of combat will use the normal rules of combat (since the only actions the two can do is very limited).
Also, I don't see any big reasons to use hidden combo rules with grapple (just because of the limited choices both sides have).