Can't comment on insurance since I've never had to make use of it. I do go for insurance if I think I'm driving in a crazy area full of people who can't drive i.e., Vegas, Vancouver, etc.
Other things to note for first time car renter might be:
Bring your driver's license and credit card at pickup.
Don't be surprised if you don't get what you had "reserved".
Prepay a tank of fuel and return it with the fuel light on. If you're flying, it sucks trying to find a gas station near the airport while potentially running for a flight.
Make sure your rental has unlimited mileage or keep an eye on how much you drive.
Stick with the major rental companies that you've heard of like Hertz, National, Budget, etc. If rental location is even slightly offsite from airport, there's likely a free shuttle.
Check that they're actually open during the time/day you're wanting to pickup/drop off.
Someday we may need to activate the halo structure off Deerfoot and destroy the North East.