You'll probably need a longer chain. If your old forks take a 1-1/8" headset, they should work fine. Your chainring should fit fine, you may need a spacer. Get a smaller one when you have the cash. The headset has nothing to do with your bars. If the forks fit, the stem fits, you can use your old bars. A 4 pawl hub has twice as many pawls as a 2 pawl hub. They're the bits inside that engage to make you go forward when you pedal. The bottom bracket is technically the bottom tube of your frame, where the cranks mount. It's also what some people call the spindle that fits in there. You need to know what your new frame has, in order to get the proper spindle. American is the big one, since way back. Euro is the newer one, which is smaller.