Hello Nicolas,
I just installed Joomla 1.6.6 and i added hikashop. After install, i deleted all new hikashop created tables in database, uploaded existing ones and copied media/com_hikashop folder. Everything seems to be ok, except one thing:
-in our website, users are registered by admin. So, i selected "No registration" in Users Manager and also in Hikashop configuration.
The problem appear when user is logged in. When a user (not a guest) go to checkout area, the app require email? and delivery addresses. The email address field is already filled, but when the user completed address fields and submit information, will get the message: "Please create or select an address".
Checkout workflow is: login_address,payment_cart_fields_confirm,end