A: Similar to the way in which a monster's Resistance Points are grouped together into one lump number to help speed up combat and make the Storyteller's job a bit easier, each monster's "Advantage Modifier" is meant to be a fast & easy lump number that Storytellers can add to that monster's CAST rolls. It does not have to be their total CAST roll modifier. The Storyteller should feel free to include other/additional Advantage Modifiers (bonuses or penalties) if they deem them appropriate.
A: Enemies and monsters (unless specifically stated otherwise) get one attack per turn. When you see "- or -" between their "Attack" types, it means that enemy has one or the other. For example, rune witches have a dagger -or- a curved dagger. The Storyteller can choose which type she has, but she doesn't have both. When you see "- and -" between "Attack" types, that means the enemy possesses both options (but can still only attack with one per turn). For example, a grizzlok has bite -and- claw, because it can both bite people and claw people, but it can perform only ONE of those two attack types each turn.
A: I'm not sure if that was a typo or an oversight on my part, but you're absolutely right – Glaive should have a damage of d10+2.
A: Yes. I apologize (and here I thought I'd managed to catch all the typos). :) On page 54 of the rulebook, under the Enchanter power "Great Enchantment: Weapon," the example should read: a damage of d10+5, NOT a damage of d10+2.
A: It's really up to the Storyteller, but the basic rule of thumb is this: what could the character realistically do within the span of a couple seconds? Freebie actions clearly shouldn't be unlimited. For example, a character probably shouldn't be able to drink more than one potion in one turn (unless they're spending their entire turn drinking a couple potions). If you're the Storyteller and you run into a situation where you have a Player trying to squeeze more out of freebie actions than he or she should, I'd recommend setting a limit. Simply tell the Players that you're limiting freebie actions to 1 or 2 per turn.
A: Moving can be considered a freebie action up to 10 feet. As long as your character is moving 10 feet or less, then they can also attack an enemy (before or after moving) in the same turn. If your character wants to move more than 10 feet, however, then that movement must take up their entire turn and they cannot attack.