< Speaking of which, would Makoto be able to use his ability to use The
< PowerKey Staff to duplicate Ifurita's abilities? 

Considering that the end of El Hazard had Makato holding the staff
when he teleported back to earth, I would say yes.  Also, it seemed like
some amount of time had passed between when Ifurita first left, and Makato
came back to her.  He seemed alot older.  My Tenchi Muyo/El Hazard/Fushigi
Yuugio (shamless plug) fanfic coming out next year is going to take
advantage of that time gap...