The County of Brant has a bylaw for fireworks. It can be found at http://www.brant.ca/fireworks , along with the answers to your questions.
1. Do you have a consumer fireworks by-law?
2. What are the sales restrictions within the by-law (days permitted/amounts displayed/etc.)?
1 week on either side of Victorian Day, and Canada day for sales and discharge
3. What days are firework discharge permitted?
same as sales
4. What are the charges and fines for by-law contravention?
I’d have to check with bylaw.
5. Who handles the enforcement of all parts of the by-law (sales/permits/discharging/etc.)?
Fire handles sales, and bylaw/OPP handle enforcement.