Still no way to have Keyboard Shortcut that duplicates function of the toolbar "rewind button"?

You can define keyboard shortcuts for previous/next measure. Pretty much the same, except that it snaps to measures. You can keep the key pressed for fast forward or rewind.

W is mine. RTZ is the term.

IIRC I had to manually bind "W" to the rewind function after upgrading from 8.5, where "W" had been the default.  And has been the default since Cakewalk 1.0 for DOS. John's right, the proper term is RTZ, or Return to Zero, which makes it difficult to find in the keybindings dialog if you're looking for "rewind".

That's because RTZ is not "rewind", it's a reset. Whereas rewind and fast forward are "motions" specific to physical media like tape, RTZ is instant. That's why you have 2 different transport control buttons.
 
Perhaps confusing is the online documentation defining RTZ as "Rewind to the start of the project", when it should say "Skip to the project's current start point." This is not always the beginning of the project but could also be the beginning of a specific loop selection.
 
RTZ's opposite is Go To End or GTE.
 

One reason I use a CS.

I keybinded REW/FF to the number pad 7-RW and 9-FF once upon a time before I had a control surface that had a jog wheel. To be honest, I might even do it again as it does have its uses.
Just look in preferences. you can set it up there.

I want
NumberPadMinusKey to rewind
NumberPadPlusKey to FastForward
 
Looked at Key Bindings. No way to do that as far as I see.

off the top of my head, I cant remember which ones they are.
but look in preferences/keyboard shortcuts.
it might take some experimenting but you will find them.
 
If you cant, I will try later and let you know the names of the bindings.

All the number pad keys are there just after Space [RSVD]. Just tried it and it works in X3 anyway.