3. I just had a quick skim-read of Disassembled, and it all happens in one day, with Tony 'drunk' at the UN in the morning (possibly early afternoon- the Avengers at the mansion are eating some kind of meal together, but I can't tell if it's breakfast or lunch), and Wanda being taken away by Magneto at night. In Iron Man #86 it shows Rumiko watching the news but being unable to contact Tony throughout the day, so the next day she gets on a plain to go to America. I'm afraid I don't have time to look through the entire story-arc right now, but I would guess it was that day (the day after 'Disassembled') or the day after that that Rumiko is killed.
The devastating thing about Disassembled is that everyone loses so much over just a couple of days. (It should be noted though that Tony doesn't officially disband the Avengers until 6 months later. I don't really know what was supposed to be happening during those months though, so if the date doesn't fit your plot, I'd say just ignore it.)

As for where Extremis falls on the timeline, that's something that's perplexed me for a while too!