the thundering1 wondered ...

As far as shooting "fast" and having to worry about saving files - how
big is the in-camera buffer?

The online manual and the web site are curiously silent about this issue. 

Got any idea how many RAW shots it can fit before needing to stop
so it can write and make space?

The online copy of the manual states that CCD-RAW is not available
when using only the internal memory.  This suggests that the internal
memory is not large enough to hold even a single RAW file. 

HTH but YMMV

--
MGD