1. Yes just leave and keep it as it is. No issues.
2. To use an ID in the banks in US, its better take your passport as some branches/bankers will say ok for Canadian ID and some dont.
Other than that you dont need US identification hence you dont need ID from US.
3. Yes, just continue as usual as per view.
Just declare income in your 1040 and you should be good.
4. Yes. Refer this link for taxes and exemptions
https://www.canadavisa.com/canada-immigration-discussion-board/threads/taxes-payroll-working-in-us-living-in-windsor.551077/
5. You can use H1 for visit/leisure purpose during weekends/anytime but watch for covid restrictions if they have any ban on non-essential trips.
Dont ask me for any rulebooks and links.