Wow, someone actualy wants to come to Tallinn
Check out Jaama market. Lots of old cameras there. Mostly FSU though. Its right next to the Old Town. Its should be visible from the Patkuli viewing platform.
I could show you where the stores are, but im leaving for a week.
There is
Fotomeister next to the department store (which is next to the Viru center). There is
Fotohaus somewhere too.
Photopoint is probably the best place to get film. There is one in Ülemiste center near the airport. There is one more in Tondi (this one has used gear too). To get there sit on tram number 4 (Ülemiste-Tondi direction. Should be written on the tram, but im not sure.). Go off at Kalev stop, and its about 100 meters from there.