I'm sorry to say, but I don't think that N800 is quite there yet. Nokia is selling it as a Internet Tablet, so most of the PDA-functionality isn't supported by Nokia because it is developed by others and just ported to N800. This is a relatively new platform, and I strongly believe that in time it can do all the things you described and more, but at the moment it is still a work in progress.

I think that the main thing is to keep an open mind and remember that some things are done differently in Linux. It's common to try to use it like windows, and then curse when it doesn't work the way you expect it to. If you're interested in linux generally and not just the N800, you could check out Ubuntu. It is a linux distribution that is created for end users and has a great user friendly community base. Both Ubuntu and Internet Tablet OS are based on Debian, so knowledge of ubuntu will help you better understand your IT too.

It is often easier to write instructions using command line instead of taking tons of screenshots or explaining the sequence of buttons to press. So if the guide is only for command line, it doesn't mean you can't do the same thing with dialogues. Anyway, you shouldn't look down on command line. It is really a powerful tool once you get to know it.