as i said i cant get on to the samsung website to double check the data sheets, should be able to get my backup of them tonight so be patient, the kernel will need a patch but it should be trivial to add/write
that part number looks like aflash chip to me, you would have not been ablee to find it as you added the temprature range and speed identifiers to it as well, try stripping the last letter off the end one by one until you find it
the ram chips are under that big metal thing
however the chips have to be the same number of pins and pin compatible, there is a work around if they arent but its not pretty, the plus side is that you would be able to do up to 1 G if there is space
usb hub is doable if you can find one thats small, but you will lose usb client without some clever hackery. just post back for details
for big battries i recomend the big psp power packs from www.liksang.com they are 5 v and correct polarity and are 4.2AH each even thogh its external it means you can hot swap them for war driving action
i think you might run out of space (as will i) but i was thinking of getting a machining guy to do an aluminium bottom plate to replace the exsisting bottom from cad plans, that way i could use it as a heat sink for the cpu and make the internal area biger (but also bieng bigger overall) this would allow me to pu a full usb port on the back and redirect the power so it can do 5v @ 0.5 A, all i have to do is fnd someone to do it and mesure and draw up the bottom plate, might even do the entire case.