No.
About $150
No,these were mostly made in Yugoslavia,with some early rifles finished in Manchester England.
I don't know of any published data that exists for these firearms.
i bought the firearms leagaly in december 2012
About $350, depending on condition. Factory engraved model higher.
Remington
100-500 USD or more depending on specifics
There were two companies known as Interarms. The first was an importer/exporter, formed in 1953. They did not manufacture firearms. The second - and current - Interarms is a subsidiary of Hi Standard, and does not manufacture a PPK or PPK/S pistol. If what you have is actually a Walther PPK/S, value could range anywhere from $300 - $800, depending on specifics.
They did not make firearms. They contracted with makers of firearms to put their name on the firearms they bought.
Remington bought them.
at the mossberg firearm factory.