So since the update, the hero got more love and i got some questions
Please no speculations, i want the real answers
1- can we use hero with different weapon in defense during gw and will it count as different troops?
2- if i want to use different hero class, is it safe to wait until the day is locked to switch my hero class in defense for the next day?
Or it will also change my hero class for the locked day?
There hasn’t been any mention of hero mechanics changing outside of talents being added to classes, so I think it’s safe to assume nothing in relation to GW has changed. But good luck with getting your answers 
We can (still) use the hero multiple times with different weapons and have it count as different defense troops.
Changing the hero class (or talents of a class) will change it on everything. Probably. I don’t think the defense team lock will save the class you selected beforehand if you change it afterwards.
def team lock doesnt save what class. Have done it before without realising, and it changed it for then too