The Booking Calendar is support the WPML, please read more at the FAQ of plugin site at the translation section.
Also its not support the changing of the currencies at the client side of site. The visitor will see the cost only in the currency, which you are set at the Booking > Settings > Payment page. I think the possibility to change the currency will be available at the payment site (like paypal) page, when the visitor will be finished the payment.
Also please note, because you are mentioned the "publishers", in the Business Medium versions is exist only one booking admin panel, its mean that the bookings and the booking resources will be visible to the any wordpress users, which is logged in to the admin panel. May be you are need to check also the MultiUser version, where is exist possibility to have individual booking admin panels for the each of the WordPress users. Please test it at the live demos.