The disc brakes are Avid BB7. They took a day or two to bed (with me purposely slamming on them at red lights in Manhattan traffic). One morning before I knew they were 'ready' I pressed them hard and as my bike came to an almost complete stop one of my feet almost slipped off the pedal and I very nearly went over the bars very slowly. Good brakes!

1" headset and 1" fork. Take out old headset cups (frame incurred a scratch or two because I insisted on doing it myself without the proper tools), press new ones in (very easy with a long bolt and some washers), put new crown race on fork (my lbs did that in a few seconds for free, but it can be done at home).

I've heard that 1" threadless is not the safest but considering how hefty this disc fork is I am not worried in the slightest. Maybe with a 1" carbon steerer or something you'd have reason to worry.