Yep, just the one. It works really well; I can crush it and it gets just to the point of almost locking up, but doesn't, at least it hasn't in all my tests with it so far. It has great feel and modulation (unlike my mountain bike which sends me over the bars in an emergency stop).

No need for a chain guide. The ultegra is a mid cage design, I think they come in short and long cages as well. I probably could've gone with a shortcage since there's no front derailleur. I like the Alfine with the builtin chainring protector thingie, haven't had an issue with chainprints on the pantleg.

It was a bit of an experiment but I really enjoy riding it so far. If I lived in a steeper area I'd probably go with a front derailleur, but it's working alright for now!