Inertron was the General Product hull of the Pre-Crisis and the scrith of the Post-Crisis, AFAICT (for those who have read some other Larry Niven works besides Man of Steel, Woman of Kleenex).
The portrayal of x-ray vision has been inconsistent enough even without throwing lead into the picture. Does he emit x-rays or not, and would he emit x-rays as part of the "heat" that heat vision could generate even if he couldn't see through things? How does he know that Lois' underwear is "pink", when there's no visible light shined upon it? How does he handle depth perception in the context of x-raying -- how does he figure out how not to x-ray the eye chart in the room next door so he can serve in the Army?
Another idea I had about how x-ray vision works from decades ago involved the Phantom Zone, where really he's "projecting" his sight into the Phantom Zone and thus it can pass through things. Of course, how the heck does the Phantom Zone work?
Alan Moore's Supreme captured it best -- I see, I hear, I know.