"The accelerometer can also be used in games and third-party applications such as Bounce which comes pre-loaded" Bounce being pre-loaded is speculation. It is not listed anywhere to be pre-loaded.
"Premium services must be bought in order to get voice-guided navigation, traffic and safety camera information, premium travel content, 3D landmarks and weathe" Voice guided navigation has not been announced AFAIK.
"Application development support" mentions C++, Qt and python, but not C/GTK+. Only C/GTK+ is actually officially supported for now.