Problem with changing the fork to a rigid one for road use is the disc brakes. One fork I can highly recommend is the Project ll that used to be fitted to Konas. Good fork that I know and they do a disc brake version. Not cheap though. But talk to your local LBS- they may have a cheap supply from a manufacturer that will fit.

Bike fit---I was fit when I started cycling. Still took a couple of years before I could comfortably do the regular 30 mile offroad ride that me and my mates were doing. And it was 18 months before I rode all the way up the 1 mile 15% hill that was in the middle. Being fit and Being Bike fit may seem similar but Bike fitness take a while to aquire.