USA Vendor selling to Canadian Customers

We are considering sales to Canadian customers.  I am looking to see if anyone has set this up already? Has anyone just set up the sales under a Nexus or did you find you had to set up a subsidiary to handle the business? Do you bill your credit card Canadian customers at USD and then let their bank convert to Canadian currency or did you set it up to bill at Canadian currency? How did you handle the open accounts billing? Did you have any problems or issues calculating, collecting or remitting the different taxes?
Any experience doing this that anyone wants to share would be greatly appreciated.  We sell ladies, sports and tech accessories and we would not  open an actual office in Canada - just considering a sales rep in Canada.