1) When there is no (null handling) function (such as "like") to conflict, do we still want to have "_withoutNull" in the name or should we go back to the simpler name and just IMPLY or comment that inputs should not be null.

When we DO need two functions one for possible null and one for WithoutNull, the first function should handle null and then call the matching WithoutNull function so the implementation details are coded in one place.

2) For example, getObjectValue gets this right, but getObjectLength does not (mostly duplicates code).
There may be other cases.

3) Pick a convention and stick with it "WithoutNull" OR "_withoutNull".
NValue is selective about using "_" in method names for certain specific patterns like op_... 
I like the idea of adding "_withoutNull" to the patterns that deserve "_" treatment -- to make it clearer that the difference with the short-named function is minor and it follows a regular pattern.