The stuff that didn’t fit in anywhere else is documented here.
Controls whether a final newline is enforced when the file is saved.
The value is an association list that for each language mode specifies
the value to give to require-final-newline (see Saving
Buffers in GNU Emacs Lisp Reference Manual) at mode initialization. If a
language isn’t present on the association list, CC Mode won’t touch
require-final-newline in buffers for that language.
The default is to set require-final-newline to t in the
languages that mandate that source files should end with newlines.
These are C, C++ and Objective-C.
If non-nil, the syntactic analysis for the current line is shown
in the echo area when it’s indented (unless
c-syntactic-indentation is nil). That’s useful when
finding out which syntactic symbols to modify to get the indentation you
want.
If non-nil, certain syntactic errors are reported with a ding and
a message, for example when an else is indented for which there
is no corresponding if.
Note however that CC Mode doesn’t make any special effort to check for syntactic errors; that’s the job of the compiler. The reason it can report cases like the one above is that it can’t find the correct anchoring position to indent the line in that case.