Some additional points:
"High end places" are not that interesting at Berlin. Let me know if you are looking for something specific - i might have an idea. If you must (because you travel with your girl/wife), see Quartier 206 (especially "Departmentstore@206") and Galeries Lafayette (both on Friedrichstr.) or "The Corner" (Französische Straße, just off Friedrichstr.) - the most famous boutique (and a little bit like Colette in Paris). Avoid Kurfürstendamm and Kadewe - it's a waste of time. If you are looking for classic scents and shaving equipment go see "The Different Scent" at Krausnickstr. (in Mitte as well).
There are some nice stores between Hackescher Markt, Rostenthaler Str., Münzstr., Neue Schönhauser (all in "Mitte"). Might be of interest. "AM1 AM2" at Münzstr. 21 is a very nice Boutique there - they have some nice stuff, for example Margiela, Dries van Noten, Valextra.
You may find decent shoes (from England) at von
Truchinsky or
Schuhkonzept .
There are a lot of vintage shops in areas called Mitte and Prenzlauer Berg (Oderberger Straße, Kastanienallee, Neue Schönhauser). Most of them are a little "trashy" as well.There is a huge flea market in "Mauerpark" on sundays wich also provides a lot of low end "vintage" stuff. I am not sure if this is what you are looking for.

There is also a very nice flea market at "Straße des 17. Juni" on Saturdays and Sundays. You might find vintage watches, jewlery, luggage etc. there. There are some stores with antique watches and jewlery in an area called Kreuzberg around Bergmannstr. (cloesed on sundays).
Most of the "second hand" stores will have some army stuff - mostly from the former eastern german army (NVA). There are some guys selling fake army stuff from russia at most tourist places like Checkpoint Charly.
Eating depends a lot on your prefered price range in Berlin. There is a lot to get on the lower end - which is mostly not that good. You should have some "Currywurst", which is a local hit. They have decent currywurst at "Kadewe" - a huge department store most people visit. "Konnopke" at Schönhauser Allee in Prenzlauer Berg is very famous - I don't like it.
There are a lot of restaurants around Potsdamer Platz - no recommendation from me. Very standard stuff, a lot of hotel restaurants, aimed at tourists.
The best restaurant in Berlin is
Fischers Fritz - in Mitte and close to Potsdamer Platz. It is classy and you will spend 150 Euros plus a person. If you like to spend less - let me know what you like to eat and what price range you aim for and I might have an idea.
The best coffee in Berlin: Bonanza Coffee Heroes at Oderberger Str. (Prenzlauer Berg). Crowded on Sundays.
Regards,
Max