Oh, thanks for mentioning Xournal... when installing it I somehow hid the top menu immediately (F10?) and thought there was no preferences menu to enable right-click erase! That's what I meant by slow. After looking into it, I've updated the page to recommend it more highly.
The 3 points you got stuck were definitely intended to be the hardest, but for puzzle 1, looking up lists is absolutely expected/recommended. I think I'll add that info somewhere to the no-zero edition, since I put "using an encyclopedia is permitted" on page 0.
I'll also be pushing the latest updates to no-zero edition since lots of people seem to be downloading it. Though I'm not sure I recommend that version.