We don't have a way to pass arbitrary parameters to 2CO, but for language you might try selecting your preferred language in Seller Admin > Account Preferences > Default language in checkout page. Buyers can also select their preferred language on the 2CO checkout page where they enter their card details, in the right-hand sidebar.
The buyer's name and email will always be collected during checkout, and there is no way to bypass that, so there is no need to collect a name/email by other means unless you expect those details to differ from the actual purchaser's identity.
