http://www.amiga600.de/Ultimate 600 clocking and hacking site, including USB, Apollo, cooling, 10GB HDD (Now obsolete for Amigas, use a Microdrive at 8GB or if larger is needed, an iPod drive: They all connect to an ATA bus.
Remember that this isn't a notebook motherboard, so the power drain of the system will probably be severe. You MIGHT get away with a modern battery (Typically around 5000mAh at 10.8V) Although you'll have to come up with the wiring.
As far as screens go, laptop panels are a no go. You simply cannot interface them to the motherboard. Portable game LCD panels are usually OK, (PS1 screens are small but popular) as they are composite connected.
A1200 and A600 have compatible keyboard interfaces so it should be possible to adapt an Amiga 1200 kbd-PS2 adaptor to an Amiga 600, and use a PS/2 Mini-keyboard as the keyboard for an Amiga Portable.
I did alot of research on this in my early teens, if you hadn't noticed. My "Tomato" amiga never quite got finished, but I still have all the components in a box somewhere.
Yes, you can use the stock Amiga 600 keyboard but the keys are kinda chunkay.
Don't bother with an internal CDROM. It's honestly not worth the hassle. PCMCIA CD drives are cheap enough, and if you manage to add your networking over USB, then your PCMCIA is free for you to play with.
I'm pretty sure an A600 with a hard disk will be fine as far as booting with no FDD installed goes, if there is a problem, aminet hardware hacks or Amiga600.de will have the fix.
The 1200 board is a much better board for use in a portable system. I recommend you use it instead if you can get one. The compatibility with CF, PCMCIA etc is as good or better than the 600, AOS 3.9 is more compatible with it, you also have AGA support and a decent upgrade path to speed up your Amiga a bit. The glue-on clocking boards are a PITA. Finally, on the note of the A1200 board, the A600 keyboard works connected to the 1200 slot, I tried it once as an experiment while designing tomato. Serial Trackpads are rare but available, there's one in my design. a driver exists on Aminet.
The Susanne was amazing at the time, but hardwarehas come along way, and with relatively cheap and common modern components, a reasonable Amiga portable can be built. Just use the 1200 as a base.
