Seems like some of it is very useful, although the Bit Commands could be realised in Blitz easily:
These functions were included from a previous request, and there are ways to set these bits in code, but if speed is a concern, the DLL can modify the bits in 2 or 3 CPU cycles/per call, whereas your example would require many more by performing at least 6 math operations.
As far as threading, i'm not sure Blitz3d is thread-safe.