Thanks for the input. I knew it was a bit railroad-ish to make the characters want to free the woodsman, but they have no other reason to want to go the the prison. I'll think about this as I work on the second arc.
Running skill challenges never goes to script. I always let players run with their own ideas rather than sticking to the text. The notes are almost for my benefit rather than theirs. Good point though, I'll never think of EVERY way that a PC can beat a challenge. I will take a look at the failures and maybe add some triggered developments.
The mountain man attacks the party only if they try to cheat him at cards and get caught. That wasn't very clear in the text. And sure, the PCs can do it without him, but having the guide along gives a +2 bonus to all skill checks as he is familiar with the terrain.
Thanks again for the feedback, should help make the adventure come out better.