Do a significant amount of research on the diameter of the replacement bars and how you mean to mount the controls. Road and mountain control clamps do not interchange well on differing bar diameters.
This is just one of the reasons that aside from the specialist flatbar control sets from Shimano and Campy, many hybreds have mtn control groups. This requires a good deal of research into derailleur and brake ratio's.
If you buy a straight up road bike, you may well have to replace much more than just the bar/stem combo to complete the job.
Other than that, I think that this is one area in which becoming more of a mechanic pays real dividends. You can analyse those parts of the bike that meet your own needs and adapt them to fit your own requirements better than any pure store bought bike will.

Im starting to like your helmet more and more, it sort of grows on you. Would it be possible to get sort of a hinge thingie so that the wings could fold back on downhills.