Auto attacks are something completely different in Divinity than they are in games with real time combat. It's only that those games gave them a really bad name - especially the bigger MMOs. They are an integral and important part in Divinity and completely different from auto attacks in most real time games.
But you can do whatever you like in a mod you make.
Enemies can use skills that are in their scripts. I don't think they use any player spells/skills but I did not check every single character script to find out. They don't need to. Enemies have spells that players don't have, so they don't need to have every spell players have.
You can do whatever you like with Lucky Charm drop tables. I can't give you advice there because the numbers you posted are far beyond my personal taste.
Any numbers you choose won't change the principal problem: very limited amount of drops in a system designed for an unlimited number (like Diablo's).
It's also a matter of personal taste. I did not care about gear from lucky charm but was pretty happy and content with the additional special arrows and ingredients it gave me.
And don't forget that Lucky Charm is not only about drops but also about offense rating.
(Same problem as with Loremaster, which is also not only about identifying items.)
The most important person you make a mod for is you, so do what you personally like most. Others might like it or not, but that is less important. If you publish a mod, you will get feedback, stuff like drop tables are changeable even for existing games. The things that cannot be changed afterwards are story scripts, placed objects and existing drops. Even character scripts are changeable for existing save games, unless they work with either pre-placed objects or work together with story scripts. (But not because the character scripts cannot be changed but because story scripts cannot be changed.)
