Can only talk for our SOPs, which come from Boeing.
if the fire is indicated before V1, is it STOP - then deal with the fire, or deal with the fire first?
You're accelerating towards that V1 speed quickly so it's always do the stop first and either pilot can call stop. There's no time to go into analysis of a false warning at that stage, if you get the bell/warning message(s) it's a stop.
Only when stopped do the checklist ( and yes, for the fire drill there are items done from memory).