I will probably need help, but I would like to get as much as possible done by myself, before requesting premier support.
Location is already set up. On our main website (http://www.segufix.de/detail_en.php?recordID=1) pricing is hidden for users from the US, shown in CAD for users from Canada and shown in Euro for users from all other countries.
So I think the right price would be put into the cart. This is not achieved with a session but with the user's IP address and temporary classes. And here I am not sure, if temporary classes can be implemented for the use in the cart or choosing the right cart.
Would I be right, that I have to add a second cart in order to specify other tax rules, shipping cost etc.? Tax rules in Canada are tricky, because there are different tax rates for different provinces.
Edit: On our web shop sessions is used for language choice. Can it be used for location too?