World-of-warcraft – Repairs during raids – What are the options

They're all still available, even though they make no sense chronologically (as admitted by Blizzard).

All the dungeons are the same numbers as previously - 10 and 25 man for the ICC raid, and 5 man for Forge of Souls, Pit of Saron and Halls of Reflection.

They probably can't be soloed, but there would be very few people running them now that there's new content.

The only dungeons/raids removed as part of Cataclysm was Zul'Gurub, the old level 60 20 man.

Cataclysm raids are tough. The bosses hit like trains. And Realistically, after a few seconds, Vengeance makes threat pretty trivial.

Don't worry about hit/expertise. Focus on stacking Mastery to improve your survivability. In a raid setting, you'll have Tricks/MD's that can cover the first few seconds of threat for you while you get Vengeance stacked if you get a string of parries or misses.

Hold onto any Hit or Expertise gear you come across though. There are some niche/gimmick uses where you may want to stack those stats, and of course, as you begin to outgear the content, shifting stats from survival to threat always makes sense for improving your DPS and shortening encounters.