Do I need or want preamp tone controls

Get them if you like, but just be aware that they will always lend somewhat the same signature to any program material you try to use them on, since as Sean says they are not very flexible in their action. And I would skip them altogether if there's no way to take them completely out of the circuit. As my own system improved over time, I found I no longer needed or missed tone controls for the great majority of recordings, FWIW.

I figure the people playing the music and the people in the studio know more about what the reording should sound like than I do. I leave the tone control to them.

why not better getting separate equalizer box?

Sorry Bob,
I mostly agree with you but not here, I'm afraid.
The vast majority of tone controls incur noise. Even the Cello Palette is not free from it.

In most cases, I would suggest experimenting with different signal cables, unless you want to control the 'color' of the sound of particular pressings and accept the fact that some noise come through.

Sean, my preamp has a processor loop. What EQ devices have worked best for you? Something I might try giving a "spin".