No.
Yes.Can you tippet be a smaller diameter than your leader?
Ernie
The leader tapers down to the tippet size that you want to use.
This taper, will help turn over the fly as you deliver it.
The leader is thinner than the fly line and is usually monofilament, but some people use a furled thread leader.
The idea is to put some distance between the thick fly line (that fish can obviosly see) and the fly you want to fool them with.