You can find many of the answers to your questions by using the search feature in this BBS. I'm a total I-appliance newbie and updated a GCTP with a 6 Gb hard drive runnning win98Lite by using info found here. I'm actually using the GCTP to reply to you.
Here are some answers to your questions:
1) Yes but I don't have them on the GCTP I'm using right now. Try searching on this BBS.
2) Yes, the GCTP I'm using has a IBM Travelstar in it. I bought an IDE connector and custom cable from Bigdog and soldered it on myself. Works great.
3) The processor is soldered on. Upgrading would be pretty tough.
4) Video is pretty slow.
5) No problems with durability but I haven't been moving it around a lot. For kicks I'm going to test it in my car.
6) Don't know about the PCMCIA slot. Could be pretty challenging.
I had a lot of fun with this project but it was quite time consuming and the system is a little slower than I like. But it's fine for surfing even with Win98 and plays MP3 OK. Just can't do both at the same time very well.
The Midori route sounds like the best but unless someone creates the image and posts it I'll stick with Win98. I'm to much of a Linux newbie to even give it a try.
It certainly was fun and rewarding.