Also, is the comma in a list different from the operator comma which is noted as right-associative precedence 5? I had thought that the item separator in the list was special syntax that had very low precedence.
The _colon_ is a non-rebindable special-syntax operator with infixr 5.
Otoh, the _comma_ in a list is _not_ an operator but merely an item separator.
Comma-separated list notation e.g. [1,2,3] is special syntax that desugars to e.g. 1:2:3:[].
Other than that, the colon and comma don't have anything else in common.