1. You will be able to share files with Windows/Linux over Samba when the new OS comes out. Right now, I don't personally know if there is any port of Samba. Check maemo.org.

2. It uses the internal memory. The only way around this is to clone your operating system to the SD card and boot off the card. The process is outlined in [1] (caveat: the term "MMC" is a hangover from the days of the Nokia 770, so please interpret it as meaning "SD" for the N800).

3. One way would be to click the power button and select "Lock Touchscreen and Keys". For another way and further information, see [2].

[1] http://maemo.org/community/wiki/howt...from_mmc_card/
[2] http://www.internettablettalk.com/fo...ead.php?t=4625