Oldest One's page

If my character falls through a square threatened by an opponent does it provoke an attack of opportunity?

For example:

My character is on top of a cliff being chased by an angry drider. My character falls, passes through the driders threatened squares on the way down. Does this provoke?

I'm looking to run a session with a mass battle as a backdrop for the events going on with the party, but I'm running short of ideas for encounters. I don't want the entire session to be constant combat, I'd like a few encounters to be resolved via skill checks and roleplaying.

For example: The characters come upon a group of NPC's trapped within a burning building, and need to figure out a way to get them to safety.

The scene is the PC's have arrived with a caravan to a Grippli village in a vast jungle. The village is empty, the inhabitants having been slaughtered in a Tsathar (evil frog men) attack. The Tsathar have hidden themselves in a now fetid lake and wait for nightfall to attack anyone foolish enough to investigate.

The PC's are level 5.

The Alchemist class confuses and frightens me. Perhaps some of you nice people can answer my questions:

1. Is using an extract the same as casting a spell? For example, if you provoke an attack of opportunity while using an extract do you have to make a concentration check? Can you use an extract "defensively" to avoid provoking?

2. What kind of action is it for another character to use one of your infusions? Can a character (who isn't an alchemist) draw and drink an infusion as a standard action?