I have a Seamaster 14k that I want to serve for a reasonable price.
Where/how do I get my glass polished? How much should it cost?
(I am located in Berlin/Europe.)

I have this monocoque case from what I understood. Do I need to go to a Omega store to get it opened or could I do it at normal store that serve watches?
(I would like to make some pictures from inside to be more sure if its solid gold, what year it's from and the Caliber.)

 

A good watchmaker can do the job. Im sure you can find one in Berlin.
No need to go to Omega.

 

Whatever you do take that horrible stretch bracelet off before it does any more damage to the lugs.

 

The crystal looks like original - can make out the logo. If you have the time - buy a tube of Polywatch on ebay and the minor scratches can be removed in under 10 careful minutes.

 

Prioritise having the movement cleaned & oiled by a proper independent watchmaker. Not Omega itself.
Polishing the crystal can be done yourself, at any time.

 

If it says 14K then it should be solid gold unless it also says Gold Filled or Plated. There should be a hallmark, probably inside one of the lugs. Date 1963-65-ish.

 

The bracelet currently on the watch either never had expanding ends or they were removed, so at least that one, while not the most attractive, likely won't do any damage.

Tom

 

Steel is harder than gold, so it wears a little with each movement of your arm. Leather is better.

 

Those nasty things don’t have to be spring loaded to cause that kind of damage.