1 - 1Gb, see next #
2 - if you are a noob, with 1Gb card you won't have any kind of problems, everything should work fine just out of the box.
3 - MaemoMapper, Xournal, FBReader... for everything you need, have a look at planet.maemo.org. On the PIM side, I am currently trying winzig and at the moment I think it's the best one I tried 'til now, but you have to install python.

my 2¢