Serpent cipher : Osvik S-Boxes confusion and test vectors
To answer your questions in order:


You won't find test vectors for the s-boxes in the submission - the
s-box functions are implementation specific optimisations,
especially the bit-sliced s-box functions like the Osvik and Gladman/Simpson, which actually compute multiple s-box lookups in parallel.
If you need to test your s-box implementations, I would take the s-box functions from the implementation you're trying to replicate and generate test vectors yourself in isolation.
The difference in the s-boxes between the paper and the C source file is explained on the homepage of those two resources: "...Since then I have made further algorithm improvements, and results optimized for 3-way parallel execution are used in my implementation...".
It looks like Osvik did further searching and testing and came up with better (for x86/x64 architecture probably) s-box functions after publishing the initial functions.
I can't see anything obviously wrong with your approach, but I would recommend picking one of the implementations to compare to and generate some test vectors directly from the s-box functions to be certain.
This is the approach I was planning to use to integrate the Osvik s-box functions into a library that currently uses the Gladman/Simpson ones - I'm glad you pointed out the inconsistency in the paper/source.