I18n / internationalisation
requires variable
In the modules list under enable Multilingual - Internationalization, Variable enable a whole lot of stuff and also under XML Sitemap there is a setting you can use.
In Configuration -> Regional and Language -> Languages:
Add the extra languages, set the default and order the list by dragging. In the second tab set how the languages are detected.
In Configuration -> Regional and Language -> Multilingual settings:
variables tab: site information - select default front page
node options tab: Hide content translation links on and Language neutral (Recommended)
Strings tab: select all translatable text formats
In Configuration -> System -> Variables:
Groups tab
Node Type Settings: Multilingual Support - set all to enabled, with translation
Multilingual Settings: Extended language options - set all to require language
Configuration -> System -> Site Information you can then change the homepage per language
Structure -> Content Types -> Basic page (maybe also webform or the other content types you use) -> Manage Display tab: change language to hidden