upgrade service entrance, Hardiplank siding,

Hello all: We are Upgrading an old Zinsco combo meter socket/panel circaq 1972 100A to a new 200A CH combo panel. House has Hardiplank siding, wood frame construction. That siding has fibers that are a problem when you saw it! Very messy! Q 1: Better to To cut the siding to size of new panel, or remove it entirely and reside afterwards? Q2: Best technique and tool to cut the shallow depth of 5/16" and NOT deeper so existing wires are not nicked? Many thanks! Kind Regards, Jon