It seems that you need a new battery as your current laptop battery is refusing to take charge thus it is why it's saying it's charging, but the meter drops when you unplug the cord.
From the screen shot, your fan becomes loud because your laptop is over heating, badly. I would suggest you open and clean the inside, but that's probably too much for you. Have a friend who is skilled in doing these things, help you. Maybe go buy some thermal paste and apply it to the CPU. I have no idea what you're running, but the GPU is high also. Maybe you're playing a game? Consider not leaving your laptop on when you are AFK at school or out or even setting a shop in game when you're not around. Maybe you can tell us what type of applications you're running for a better visualization of what's causing this heat.
Your ram is being used up quite a lot, consider adding another ram stick or try not to use too many applications at once. You can also try doing a clean install of OSX and go easy on the unnecessary applications by not installing them.
So happy someone got back to me. Thanx a lot.
I'm not running any games. The only things that are usually running are 'several' (10-20) tabs on safari and MSN with iTunes occasionally. My laptop's ALWAYS on but it's put to sleep... is that good enough or should I turn it off completely?
The heat problem is a more current issue (past six months) but I'm running all the same applications as before.
I'll try to do a clean install as soon as a get another portable HD to transfer my stuff to. I've also already quit some stuff in the Activity Monitor (hopefully that'll help a little).
Is cleaning the fan really all that difficult? I've done it twice on my old Sony PC... I don't know how much it differs to the Macbook Pro.