3) "number of small circular gaskets that I have no clear use for"
Not all kits are the same. One company may decide to sell a universal kit (YF and YFA) that includes extra parts, like the circular gaskets, even though you don't need them for your carburetor. It may not make sense to us but for the manufacturer and retailer, they have to pay inventory tax and have shelf costs on the number of kits they have. Sometimes it's just cheaper to include a few gaskets that only cost them pennies so that they can have one kit to cover many applications. It's for the carburetor rebuilder to know what and what not to use.
I use the original Carter spec sheet information (specification and adjustment sheets) that Carter produced for that model carburetor (example YF2100s). All the parts that make up that carburetor are listed. When it doubt, check it out.
