I'll try to answer some of your questions.

Maemo Mapper can download maps for use offline ( menu > maps > manage maps > zoom), but you'll want to set it to use the internal card ( menu > maps > manage repos > cache db). It's easy to download the maps, and then move them, but you might as well start out correctly. Personally, I have a couple hundred MB of maps on my internal card.


Also, the n800 can act as an SDHC reader via a USB cable, but no files can be open on the card(s) at the time, which means placing a swap file on the internal card "disables" it.