I don't ride with the rack when I ride hills. I do have dual brakes on my Jamie Roy so I'm okay in that department. The steepest grades around here are about 10% but I am a novice (only about 6mnths of serious bicycling under my belt). I still havn't learned to skid-stop as I'm riding on platforms.
And I'm going to stop by my LBS to see what they can do for my gears. The last time I was in there he told me a freewheel's about $20. How much do fixed cogs usually run? I'm also going to pick up some cheap tugs from him as I've yet to take off my rear wheel (only had the bike for 3 days).