From your description, those are the proportioning valves for the rear brakes, and they are needed. In this article from "How Stuff Works" it tells you more about them. The picture there shows it as part of the master cylinder which is more how it is with newer cars. Same principle however.
If you don't want to replace the entire line from fitting to fitting, you'll need a double flare or bubble flaring tool. They are available at hardware stores, or Harbor Freight. You may be able to get one from places like Advance Auto Parts with their "loan a tool" program.
Yes, there has been previous discussions on these.
Black 2000 SSEi, Silverstar Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, drilled 180 degree thermostat, Intense FWI, PCM, shift kit, and 3.4 Pulley. Solid front mount.