As far as your regulator and rectifier go, Pamcopete has developed a replacement set up that costs about $30 to $45 to do. I think they are listed in the tech section of this site. I know they are in the electrical section over at the Garage.
The regulator you can get at any parts store. The rectifer parts from Radio Shack. Lots of people have built and are using them with much success. I'm one.
Getting the alternator working right is the second most important part of building your electrical system. The igniton is #1. With out a good alternator your bike will only run for short periods, until the battery goes dead.
Once you get the alternator working, and the ignition working then adding the headlight, tail light, brake light, turn signals horn. Thats the easy part.
Studying a good diagram will help you understand just how everything works.
I like this one. It shows how the point get wired, the electronic ignition. The old style reg/rec, the later combo reg/rec. Just swap the boxes with your parts into the right places.
The Pamcopete upgrades will hook in in place of whats there. He also has an igniton setup that swaps right in also.