You will need to bleed all the brakes. When you take the lines off fluid is going to drip down from the hardline and air is going to get into the lines. What you need to do is get a flare nut wrench and remove the brake lines from the hardline that sticks out of the body. Put a rag over it to stop the dripping. Then unbolt the brake line from the caliper. Then do the reverse to install the new lines to the body and caliper. Once you have done that to all the brake lines you need to bleed them. If I was you I would buy a Mity-Vac from Pep Boys or a Vacuum Gun from Sears. It will allow you to bleed the brakes yourself and much easier than the pressing the pedal method. Get some new fluid DOT 4, Castrol GTLMA is pretty good. Use the vac to suck out all the old fluid until the MC is dry and all the lines have no fluid. Then fill the Master Cylinder with the new fluid and bleed the lines, always make sure the MC is at least half way full. You get the point. Go to...
http://www.fourthgenhatch.com/reardiscswap.html
It deals with brakes and bleeding them and how to do it and anything.