Need some help TRF with this Red Sub

[DeeTee]

I went to check a local dealer and saw this guy instock. I'm a modern Rolex guy, but I'm eyeing the vintage market. By looking at the dial, I assume it's a IV dial, but other than that I don't know too much.

Has this thing been over polished?
What's the deal with the insert? The lighter the better?
The date window looks a bit lighter than the rest of the watch, is that normal?

Excuse my ignorance TRF, just need some help from you guys before purchase.