64 bit application will not work and it's not because of the SDK it's because SDL Studio is only available as a 32 bit application.

This shouldn't bother as far as an according external interface is provided. We were able to integrate Trados 2007 by using the according API. In this case it is based on COM, and we launch the Workbench and communicate via RPC. Our application is x64, the workbench is still x86 and the communication works.
Trados 2011/2014 is using a different API (.NET provided by the SDK) In this case we use the SDK to manage TM related stuff without the Trados Studio process like with Trados 2007. As far as I know there is no way to do it like with Trados 2007 via COM.
Unfortunately we were not able to integrate the x86 .NET SDK in our x64 application (obviously becuase of binary incompatible interface) Therefore my question: Is there a x64 Version of the SDK which can be referenced in x64 applications? If this is not the case, is there a way to integrate the x86 SDK in our x64 application in another way?

More specific:

Is there a Trados 2014 x64 .NET SDK available?

There is no version of x64 .NET SDK and this is because the dependency on SDL Studio which is 32 bits only.

I would create a Studio plugin that runs as a self-hosted service. You can then call that service from your application just pay attention for the service to be available (Studio is started). If you want to create a self-hosted rest service you can have a look on how to do it here: