1) My understanding was that he was trapped in alternate time lines and couldn't figure out how to get back to Azeroth Prime. Thankfully Thrall was there to set things right (that once went wrong)
2) Because always in motion is the future. Besides, they needed all the power of the aspects to defeat Deathwing, not three and a wanna-be.
3) Because watching Malorne headbutt Lord Rhyolith was OMG COOLLLLL!!!~!!
4) Nah, Nozdormu says after DW goes down that the Dragon Soul returned to where it belonged once he lost his powers - I have the image in my mind of a rubber band, where Nozdormu's powers kept the band stretched out (the DS in the present) but once his powers were lost, the rubber band snapped back in place (the DS goes back to where it was taken) without any effort.
5) Malfurion likes doing nothing. The only thing he's better at is being a douchebag to his GF. He just needs a stained wife beater (a white sleeveless shirt for those not in the know) and a beer.
6) That gets into TFH theories, where Azeroth was meant to be an experiment on defeating Old Gods/Sargaras/Chaos. So the Aspects' purpose was to protect and guide the races until they could defend and defeat those enemies.
7) Neptulon and Ozumat have rekindled their lost love and are soon expecting.
8) You can go either way, it's either bad writing, or great writing. When you're king of Stormwind and the de facto leader of the alliance, nobody is going to tell you to stick it. OTOH it doesn't make the alliance sympathetic at all. And Garrosh is despised, just based on how the other leaders treat him and act towards him. Double standard? Yes? No? Maybe?

Anyway it's not all sunshine and roses, there are legitimate issues, but you have to remember that this like reading a book. It's like reading the fourth chapter in the Hobbit and complaining that there's no closure on what happened with Smaug.