lol I just got the medium badge by only spamming 'A' and not doing anything else because I was eating something. Two enemies wandered to the very left side and waited for the third to die before attacking me, at which point my character turned around and beat the crap out of them, easily getting the medium badge. If that works for you, you're welcome.
Since I finally found the comment I was looking for way back, apparently, you need a skill point to use the books. It would have been nice if I knew that rather than levelling a few times since then and using them elsewhere with no indication that I was doing something wrong.
I somehow did the last challenge in three tries by hitting a bit above 45 degrees at full power, doing 3 apam smashes, and having the geek going almost horizontal down at the bottom, gradually building the bar because there were so many enemies, until the ultimate smash did him in. If this manages to help you, congrats.
This has always been one of my favourite chain reaction games. Thanks for making a sequel. You actually give up more time adding on once it's posted as well.
I'm not convinced the money printers do much. I did a level with no addons and got about $8000, and then repeated it with two money printers and got $10000.
Thanks for playing!