Hello,
1) Yes, you can still use all of Auctiva's features if you choose not to offer insurance. You can disable this feature at Auctiva -> My Account -> Shipping Insurance Settings.
2) When you list through Auctiva you can only post to ebay.com and ebay.co.uk. We just added ebay.co.uk and if that goes well, we'll expand to more countries.
3) Yes, the insurance offered through Auctiva is good for items shipped from Canada.
-Mike