Open backs are pretty terrible for bass unless you EQ them pretty hard, but if you're ok with "normal" bass then open-backs are an easy recommendation for anyone. Everything Bearman says is spot-on too.
Great deal on the HD58x here:
1 - "Comfy" is unfortunately pretty user-specific, but Sennheisers are usually a pretty generic fit that most people find comfy. Replacement pads are reasonably easy to find too.
2 - I've experimented with headsets a lot and found the best solution to just be a good pair of headphones with a separate mic. I moved through a number of headsets, then a R30 lav mic and now I'm using my Logitech C920 and none of my friends can tell the difference. nVidia Broadcast does help though.
3 - For sound stage, open-backs are hard to beat. They're not quite as open-sounding as everyone said they'd be, which I found to be a good thing.
4 - See point 2
5 - Again, Sennheisers are a safe bet.