1) I can't find in the rulebook, how many times you can counterspell in a round. it states how the spellcraft check to ID the spell is a free action.
How Counterspells Work: "To use a counterspell, you must select an opponent as the target of the counterspell. You do this by choosing to ready an action. In doing so, you elect to wait to complete your action until your opponent tries to cast a spell. You may still move at your normal speed, since ready is a standard action.
If the target of your counterspell tries to cast a spell, make a Spellcraft check (DC 15 + the spell's level). This check is a free action. If the check succeeds, you correctly identify the opponent's spell and can attempt to counter it. If the check fails, you can't do either of these things.
To complete the action, you must then cast an appropriate spell. As a general rule, a spell can only counter itself. If you are able to cast the same spell and you have it prepared (or have a slot of the appropriate level available), you cast it, creating a counterspell effect. If the target is within range, both spells automatically negate each other with no other results."
As an aside, last sunday I had to run a BBEG wizard against a 16th level PC Abjurer who was completely pimped out for counterspell. Reactive counterspell feat, plus he readied every turn for a counter spell. He was able to shut down the villain's spells AND quickened spells every turn, it was frikkan infuriating.
So this implies, if the casting occurs before your initiative, you can't counter it since you haven't had a chance to do anything?
Initiative Consequences of Readying: Your initiative result becomes the count on which you took the readied action.
And if you have already done something (ie. cast a spell), then you also can't counter if someone casts at you at the end of the turn?
Readying is a standard action.
Seems like one has to use the turn and wait to counter something but you can't really do anything as you want (unless it keeps a std action free to use for the counter?)
You use a standard action to ready to counterspell.
After you've done that, if something casts a spell, you can try to identify that spell as a free action (which we assume you can use outside of your turn). If you ID it, you can then use your readied action to cast the appropriate spell. When you do so, your initiative count changes to just before the creature that triggered it. If something else then casts a spell before your next turn, you can't counter it, because you've already used your standard action and you are no longer readied to counter.
So this implies, if the casting occurs before your initiative, you can't counter it since you haven't had a chance to do anything?
Correct, if you didn't ready to counter on a previous round.
And if you have already done something (ie. cast a spell), then you also can't counter if someone casts at you at the end of the turn?
If you've spent all your actions, you don't have a readied action to counter.
Seems like one has to use the turn and wait to counter something but you can't really do anything as you want (unless it keeps a std action free to use for the counter?)
Readying an action is a standard action itself, so you could use free, a swift and a move action and THEN ready a standard action to counter-spell.
EDIT: Ninja'd by Grick