I'd like to use Vim (version 7.4) to edit TeX files using the built-in, vanilla TeX mode. How do I find out about any available keybindings that are special for this mode? Does not seem to be listed in the
There are none. The vanilla TeX mode (ftplugin and syntax plugin) defines syntax highlighting and sets some options. That's it. If you want any additional features, you have to create them yourself or use one of many plugins. See e.g. this question for some information about different plugins.