From what i can see, i have no reason to doubt that it is not real. Its certainly in need of some TLC though! You need to take the back off, and take photos of movement and inside case back to be sure though If you dont feel confident of doing this, a local watch maker will do this for a small tip ( or if you are lucky, for free, with the promise of repeat business later)
Yes its real, mid 1960s. This one does NOT have a removable back, the movement comes out from the front after removing the crown (two piece stem) and crystal, a job for the professional not for the novice.
Yes, fully genuine. It should come up very nicely after a service and a clean (but no buffing wheel!). Because they are hard to get into they aren't as mangled by fiddlers as removable caseback models are. Although some unishell cases have horrible scratches where somebody has tried to "open" the caseback.
Nice, I picked up a Seamaster Deville without the date in the same condition. I had mine recondition. Here is what it looks like now. I have the 550 movement.
The dial was like that when I purchased it. A custom job, I presume. Though maybe the forum might give some feedback.
The chemical they used to clean the dial would have likely erased the wording, so they polished all around the letters leaving the original patina under.