Can't help with the Magne-Traction vs traction tire issue, but I can say the electro couplers won't work without TMCC or Legacy control. There is no way to trigger them with a PW ZW (or even a modern one for that matter if you do not use TMCC/Legacy).
In the very early days of TMCC (1996-97) there were a very limited number of engines that had electro couplers that could also be operated manually or with a standard uncoupling or operating track. I only know of 3 such engines (though it's possible I'm not aware of one or two others). They were the GE and Southern Pacific Dash-9 (6-18226 or 6-18228) and the SOO Lines SD-60 (6-18232).
Pretty much every engine with Electro couplers since those 3 has had a note in the instruction manual that you should do traditional uncoupling by activating the coupler on the adjacent car with the Uncoupling track rather than the engine.
So if your cars all have magnetic couplers you can activate them to uncouple from the engine, but that's the only way.
-Dave