David's recent edits addressed #3 and #4.
#2 asks whether the value definition of animation-timing-function should depend on css3-transitions. I agree we should aim for a single definition.
#1 relates to the ongoing discussions about user-ident.
We now depend on css3-transitions/transition-timing-function for valid timing function values.
Only issue left depends on the final definition of user-defined idents.
Resolution pending Tab's edit of css3-values for user-defined identifiers.
All edits for this bug now complete; in particular, we refer to custom-ident in css3-values and depend on css-transitions for timing function definitions.