1- Power Conservation
General Energy Conservation (like, turning off the monitor instead of using Screen Saver)
You can follow general suggestions like turning your computer off when you're not using it (Here's some more that I didn't even know).
Energy Efficient OS
Energy conservation has recently become a big topic in OS, and you can also consider switching your OS to a more energy conservative one (a little extreme, but perhaps worth it). What the OS does is automatically switch off hard disks and pheripherals when you're not using them, switch your network cards to powersaving modes, and all kinds of other nifty things on the hardware levels. Here, check out LinuxPowerTOP.
2 - Fluctuating Voltage
I don't know = /
3 - iPod Charging
It doesn't make a difference. Your iPod charges for maybe 20 minutes a day and your computer is on for 20 hours? Comparing your iPod charging to your computer's power draw is comparing pennies to dollars, so focus your efforts where it matters (the PC).
4- Wait, 20 Hours a Day?
I think there's definitely some money to be found in cutting away some hours from your computer's 'ON' time.
I suspect that perhaps you are using your computer to do things while you are away from it, for example, torrenting Linux Distros. Consider using a different machine elsewhere to do this (perhaps a university computer), and then transferring the file back to yours. You can also try to bunch your computer tasks into fewer 'ON' hours. For example, instead of waiting till you are asleep to download stuff, consider doing it while you are typing up your homework. Don't kill your productivity trying to save a few minutes, but do look for ways to cut back on whole hours.
5- Wait, 40+ Programs?
I think there's something to be said about this as well. While loading up a program costs some energy for the disk and ram to find it, read it, load it in memory, and start it up, I think there's some energy going to waste with keeping that many programs up. I doubt that you are using them all at one time. What it does do, is cost more processing power, ram, fan-cooling, and possibly disk to keep those 40+ programs running, than starting what few for when and how long you need them (in your general case).
But in perspective, turning off your monitor is probably going to save more energy than cutting back on the number of programs at one time. So, this is a smaller thing that you can do if you choose.