1. The warriors weren't possessed and I don't see their fear of the calling as having any negative effect on their fighting abilities, if anything it should have strengthened their resolve to defend the ritual, especially since they all thought their days were numbered anyway. Granted not all of them feel right about what was going on and choose to surrender instead.
2. I'm not referring to the fortress itself, but the fighthing between Inquisition troops and Grey Wardens. I would have fallen sooner or later, just expected the troops to put up more of a fight, since the Helm's Deep'ish cinematic shows the Grey Wardens as being complete pushovers once you get into melee.
3. She was the commander, so you would expect that. And yes she certainly lived up to their reputation of being badasses. The rest... Not so much, not counting our two friendly wardens of course.
4. Sorry, can't really buy that one. If you're supposed to be guarding against a Blight that could happen at any given time and you're constantly fighting against darkspawn then you do NOT want to have a bunch of pansies running around whom don't know how to fight, or whom are easily frightened. They fight darkspawn for a living, you would think that would toughen them up.
As to why the named Wardens wereb't anywhere to be seen I don't know, hadn't thought about that to be honest (I guess it comes down to them not nessecarily being in the game depending on ones Keep choices?). I also haven't found out why Blackwell didn't get the false calling. So while I don't agree with it, I have to admit that it is entirely possible that the stronger Wardens were able to resist it. We know that Alistair and Fiona also haven't shown the affects of the calling.