1. I'm a guy so I didn't take heaps of notice but I think it was common for electrical outlets in bathrooms. Electrical outlets are very common in dorms, although sometimes there may only be 1-2 outlets for several people. This may also be determined on the quality of hostel you stay in...for the high quality ones they'd most likely have a great supply of outlets.
2. Yeah there's always space - the posts/rails of beds are almost always there to be used to dry things, or take up some rack space in the bathroom. If all else fails you can start looking at chairs, tables, doorknobs, etc 
3. Depends a bit on check-out time. If it's at 10 then its very common for it to be busy at 8:30-9:30. If check out is at 12 then its a bit more spaced out between 8-11. Also varies from person to person, you get the keen, early-bird traveller and the people who have to catch trains/planes early, vs. the people who like to drink and wake up as late as possible nursing a hangover. Also it's not uncommon for people to arrive home semi-drunk from 2-5am etc, hehe.
How not to be disruptive: pack most things (except what you'll change into/use in the bathroom) before you sleep, and know where everything is so you dont have to rummage through bags. Assuming you use a phone as an alarm have it right within an arms reach so you can turn it off as soon as it rings. Use your phone as a torch where need be (or use a torch I guess if its really handy), avoid turning on the light in the main room! If another person is up, talking in a regular voice while others are sleeping I think is rude - whisper!
[ Edit: Edited on 20-Apr-2009, at 22:36 by Erik85 ]