Organizing my digital life (part 1)

The integration of technology in my life comes in waves.  I'll buy some neat-o new gadget (e.g., a Toshiba M200 tablet, my current VX6800 smartphone), spend a few months trying to organize my digital life around this new gadget then ultimately get fed up and swear off technology forever for another couple of months.  Rinse and repeat.

Well, the cycle has begun again.  The problem this time is that I'm a grad student with a 30-45 minute commute into the city:

1. I read and annotate tons of papers all of which exist electronically on the interweb.
   
2. I carry stupid, heavy, overpriced books back and forth to class.
   
3. I write down flashes of research inspiration on random pieces of paper that I lose, or I just forget them altogether.

I really want to believe that there's an electronic solution to this problem.  Given this day and age, I should be able to carry around some lightweight gadgets that let me do all this.

My former life compels me to summarize the list of requirements such a solution will have in rough order of importance:

1. Battery life.  A good solution will last longer than the 1 hour, 30 minutes on a charge that my loaner Dell M1525 from my Aunt outputs (complete with the purple flowery cover).  By longer, enough to last during a pair of classes or research session: 3 hours.  Preferably 4 or more.
2. Portability and ergonomics.  A good solution will not be like the M1525 and be too large to carry to class, pull out on the subway, etc.  A good solution will also not burn my wrist like my Toshiba M200 tablet did when plugged in.
3. Always available.  Related to ergonomics, I should be able to pull out a good solution when I need it, and it should be ready to go with minimal delay.  A good solution also won't unduly block me from entering data that's in my head.  For example, try quickly writing a typing judgement from the simply-typed lambda calculus into a text editor.
4. Format compatibility.  I read lots of stuff with math symbols and diagrams.  Also, I read lots of old papers that have been scanned as images without OCR.  Also, some papers  are PDFs, others are word documents, more often that they're postscript files.  Besides the odd corner case, a good solution should be able to render all of the documents I throw at it with near-to-full fidelity.
5. Annotatable.  (Is that a word?)  Anyways, it follows that I shouldn't need a separate solution for taking notes alongside these electronic documents.  Notes should exists side-by-side with them instead.
6. Searchable everywhere.  Since all the data exists on a single device, I should be able to search for content across all the papers and books I have on the device.  It's not only convenient; it turns into a great research tool when you're comparing sources.

Well, I think that's it.  Does such a device or a set of devices exist that meet all of these requirements?  I don't know, need to do some more research and find out.  >_<