1. Unless you really need Ovinnik Hide for a specific craft don't try to farm it. Just skip it if you are leveling leather, and I will try and check what I did to skip it if that is what you are doing.
2. Funny you should mention that, while I don't know if there is an in-game plug-in that will do this, you could use FFXI Calculator for that. I believe I have the most recent version before it went down. And I believe FFXIGear is working on something like that.
XI Wiki



