I have a SYP bench with a traditional shoulder vise (Klausz-style). I'd like to add leather to improve grip, and have a few questions:

1) Should the skin side or the suede side face the workpiece, or does it matter?

2) The hides I have are very thin (split?). Should I double them to provide a little more give in the face?

3) Should I put leather on the fixed jaw as well, or omit it so that that surface of the jaw is perfectly coplanar with the rest of the front surface of the bench?

4) Does it matter how the leather was tanned? I have no idea on the ones I inherited, and don't know how to recognize different tanning.

5) What glue should I use? Contact cement? Bench is finished with pure tung oil (fully cured). Should I put a coat of shellac where I will be gluing, to make it easier when it comes time to replace the leather?

6) What question am I not smart enough to ask, and what is the answer?