Final Value Fees are generally lower in all categories when you pay eBay a monthly fee for a store:
http://pages.ebay.ca/help/sell/storefees.html
"I think I have to wait until all my current listings end"
No. You can open a store immediately if you wish.
Once you have a store you can list - as you wish - on all eBay sites (eBay.ca, eBay.com, eBay.uk, eBay.au, etc.) and all your listings will appear in your store, regardless where listed.
Whether your store is located on eBay.com (monthly.fees payable in US$) or eBay.ca (same monthly fees payable in lower Cdn$) does not matter. Your store and all your items will appear on both sites as long as your listings offer to ship to Canada and the USA.
For fixed price listings currently listed, you can easily incorporate them into your newly created store by simply revising them and adding a "store category". They will show up in your store within a few hours.