Okay, it's time I commented on this.
1) Is it too slow?
No. What had my mind going most was the setting. I want to know how you've mixed the old west with these fantasy elements you use/allude to occasionally.
2) Does the dialogue seem natural? A lot is said in the silences between the characters. I want to know if that's coming across.
The dialogue seems fine to me. I think the setting has influenced my perception of their conversations: time-worn, relaxed, isolated, experienced.
3) Do I need to throw in a solid hook instead of all these hints?
I'm okay. You haven't gone so far that I think I need to have some definite plot direction. It should come in the fairly near future, but I like the character development that's going on, and the possibilities that these two characters create for the story. Bill's past, the dead fugitive (a zombie?,) and things like this say to me there's going to be an interesting plot coming.
4) Does Thom seem cheery/content or frustrated/resigned in his conversations thus far?
I think he seems content and resigned at the same time. He's too tough and too close to being dead to be cheery, and he's too calm to be frustrated. I picture him here as a grumbler (with a good heart) just taking it one step at a time, maybe to death, maybe not.