Do I have to use Honda coolant on my Honda civic
No. I never have on my 1999 Honda. But if you can accept the higher price, you are getting some peace of mind for it.
No.
Just use a coolant that states for all makes/models.
They’re called global/universal coolants.
Tester
No; but use good long lasting synthetic coolant; look for a sale on “extended life” coolant