Would be very hard to do in 12 rounds, but considering how many times Bonavena was hurt and dropped against Ellis- I'd have to say, "Yes."
Yes. He could. But conversely, he could also box more cautiously if he got caught with something solid early.
Idk, it would probably resemble the Tua fight. Oscar could be very awkward and sometimes cagey with a very good chin. Lewis hesitated to open up and was prone to being gunshy or content to just jab and grab after his 2nd KO loss only firing power punches when his opponent was hurt or wide open. If Lewis went for it, I could see him potentially stopping Oscar late, but he'd run the risk of gassing out if he can't get it done. Especially if we're talking later career Lewis who was weighing an awful lot and had some flab.