Not surprising. they were supposed to be deleted in first place. They also forgot the Emperor's Vitality Tonics.
https://forums.lineage2.com/topic/24542-18th-anniversary-coupon-code-live/#comment-170036
If says "all" includes Normal and P.skill. I don't know if currently includes magic attacks.
Yes. but to understand it easier it is 4% less of target's critical rate. Is not overall 4% less.
It is restorable and you knew it already, you are not understanding the issue here. You do know you can use it, it is at your risk because they can deny based on "mood" like you noted.
After you get a decent base items best to is to stack m. crit damage and m. skill power.
M. atk boost aren't priority, and are mostly noticeable on high amounts.