I know movement cards generally ignore the rule of presence, but I was wondering if that included moving units from a battlefield to my home, most specifically through the use of the spell Scouring Flood, attached to a unit in my home, to bring home one of my defending personalities at the current battlefield.
Scouring Flood usage
A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
You should be asking these type of questions in the rules forum.
You cannot use a battle action on a personality or unit that is not at the battle. Unless the action moves him there.
No, because you still aren't satisfying the Rule of Location; i.e. the guy with the spell performing the action is not at the current battlefield.