If you're "not qualified" then why wade at all into the entrails? Just use what's obvious. If insist on going past the "simple user" boundary then you should be prepared for what lies there. N900 can be happily used without any of the Linux stuff, especially root access and dpkg. Once you take the red pill you can't blame others if it's difficult. Restore to factory defaults and enjoy your device. It's great even without the red pill stuff.