FreeFlyBertl,
I am sorry you are having so many issues.
We have a Cakewalk V-Studio 700 Set and a Roland OCTA-CAPTURE. All units (Console, I/O and OCTA) have the latest firmware. Drivers are Version 2.0.1. VS-Expand works as expected for us. ASIO buffer size is set to 256.
At first, we could not get it to work, until we realized that not all firmware were up-to-date. the firmware update fixed everything for us. Of course, having the sync cable properly connected is as important.
Do the VS-700R and the OCTA-CAPTURE at least recognize each other and report VS-EXPAND: OK in the ASIO Control Panel? If not, I assume you have checked that the OCTA-CAPTURE VS-EXPAND configuration option is set appropriately.
If you really can't get it to work and want to go the external AD route, the Focusrite suggestion should work fine.
Good luck,
Sacha