Replace the master or the slave, whichever one is leaking. If replacing the master, bench bleed the master first, then install it, then bleed at the slave's bleed screw. No matter how much air is in there, you can bleed it all out manually if the system is sealed properly.
Everytime you pump the pedal, air pressure will build up, which will be released when you open the bleeder screw. Then close the bleeder screw, and the pedal will come back up, pulling fluid in from the reservoir. Eventually, you will get all of it. the clutch line isn't very long, so this isn't like trying to bleed out brakes from a dry state.
I wouldn't use a junkyard master; get a rebuild kit for your old one instead.
P.S. Don't get brake fluid on the paint, you'll be sorry. (Wipe it up immediately if you do).
Nate