Acer :: Upgrading My Aspire 5050

I've just bought 4gb (2x2gb) of RAM from Crucial, but I'm sure that's not nearly enough, so I come to you, notebook gurus.

First things first, my battery is getting old and beginning to fail. I used to max it out on a full charge at 2 hours, but now it's down to about 45 minutes from a full charge using every battery-saving technique I can (while still keeping wireless access available). I think a new battery is in order, but I want to know if I'm stuck with generic replacement batteries, or if any of you can direct me to a nice longer-life one, like a compatible 9-cell? I like to move around my house and library a lot, so battery life is most important.

Secondly, CPU. My model is stuck with a MK-36 2.0ghz CPU (90nm). Now I know this uses the S1 socket that a lot of dual core CPU's use, so I was wondering if it would just be a simple case of updating the BIOS, then switching out for a TL-64 CPU (Also 90nm) or similar.
Is this at all possible, I'm wondering? Or am I stuck with a single-core? I've looked at this thread (linked from these forums), but that looks to be going from a dual core already.

Thirdly and lastly, I was looking at this thread linked from here (can't re-find it though) talking about upgrading the GPU, also talking about MXM. My current GPU is an ATI Radeon Xpress 1100. Is the Aspire 5050's GPU upgradeable at all? I have built all my computers in the past, but I admit I have never tinkered with a notebook before (despite having the necessary tools). Is it possible that I'd be able to shove a better GPU in there?

If there's anything I'm leaving out that you can think might be worth upgrading I'm all ears. My aim is to have the fastest Aspire 5050 I can.