I don't read PDFs or scribble, so I'll answer your other questions.
3) Memory: 1 GB MMC, any size (32 GB at least) CF, also a USB memory stick if you don't mind it sticking out the top.
4) In general the iLiad is very well made, but the black plastic matte finish can peal (the Book Edition should not have this problem). The screen can be damaged by strong local pressure (e.g. the edge of something pressing against it in a briefcase), so be careful. Recent reports suggest to me that iRex maintenance is improving, and is now good, although there are still isolated glitches. I have never had any problems with my iLiad v2.
5) This fall, there will be 9.7" Vizplex screens available. PVI will be building these with the option of a new pressure sensitive touch screen technology, see
PVI adding "touch" to eink. It is likely that several vendors will use this screen to produce "iLiad killers", targeted at "professional" use. One we are certain about (which might not directly target PDF users) is the
Astak Mentor. Its 9.7" variant looks very nice in mock-ups and has all the hardware bells and whistles - the quality of the software is unknown but the price is projected (by Astak) to be only ~$350. Slightly later, E-Ink will be bundling the same screens with Wacom technology and Epson controllers - see
WACOM and E-Ink teaming up and
Epson and E-Ink developed advanced display controller. It is unclear if anyone will commercialize this setup, but it might be better for a high end device than the (cheaper?) PVI approach.
I think the iLiad is perfect for your needs. Don't forget that new stuff is almost always: late, more expensive than projected, less capable than expected.