Re: 1., I tried powertop once but was afraid to touch anything :-) what did you do to get 9-10 hrs? I don't think I've gotten far above 7. What kind of usage? (I expect you're not running make -j4 all the time =P)
Also, for those two years, have you tried keeping it between 40-70% charged as they recommend, or have you been more "reckless" about letting it discharge and fully charge?
I turned all the powertop options on. Granted I did do this before I started using it for anything serious as a test case and left it a day. Worked fine.
To get 9-10 hours I used a 9-cell pack and keep the brightness fairly low. The screen kills it more than anything. I also have a 128Gb Crucial M4 SSD in it which is a little less power hungry than most devices. It does only have 4Gb of RAM though.
As for usage, mainly Eclipse with JDT and a Windows 7 VM spun up for Visual Studio 2010. CPU is throttled most of the time and memory usage is about 60-70%. Disk IO is fairly low once everything is up. Unity is running in 2D mode or disabled entirely in favour of Awesome WM. I don't do heavy compile runs as a rule as our dependencies are quite small and coupling free.
Regarding charging, it spends most of its time docked in an Ultrabase but when away or sitting in the garden I rarely have to bother charging it. I've got to the point I don't actually bother dragging a mains charger with me. The 9 cell pack was a year old when purchased with the laptop off ebay - neither were new. The battery had 108 charge cycles when purchased. I have no idea what it has now as I don't know how to extract that info from Linux.
Battery life is better if you install Windows on it as a rule though. I actually much prefer windows on it to Linux but I'm forcing myself to use Linux as my primary OS for a few months to see how I get on.
Windows 8 will probably give best battery life as it is tickless as well but I can't stand metro.
Also, for those two years, have you tried keeping it between 40-70% charged as they recommend, or have you been more "reckless" about letting it discharge and fully charge?