Originally Posted by
nguuuquaaa
It seems that you misunderstand something.
Recipe ------Update------> Data Drive ------Create------> Timed Ability Data ------Use------> Timed Ability
A recipe contains area, level of main effect, range of which sub-effects can take.
A Data Drive contains area, type and level of main effect, sub effect(s).
A Timed Ability Data is a consumable item contains anything a Data Drive has plus a time of effect.
A crafter will keep updating till they get the desired Data Drive (Rare Drop Up plus good sub-effects)
When you request for a Timed Ability, you request to create, so the effects are constant and determined by the Data Drive the crafter has.
Thus, you can just look for a Rare Drop Up, you will certainly get it, no worry.
And to answer your question
1. Yes, you can overwrite them on your units anytime.
2. Swiki doesn't seem to got the exact number, it's listed as significant or something