Main Daw, nuendo 6. (Or cubase its the same concept)
Second is a full blown microsoft touch screen PC.
I want to use it to automate plugins or as a control surface.
Its linked with the Wifi and also bluetooth to my main rig.
One way: Preferably link the two PCs with Gigabit ethernet, you can use a crossed cable even. Get TightVNC (free and better than TeamViewer). Install and enable as Service on the main PC. Install on touchscreen PC. Open session from small to big PC and select mixer screen, you have the main desktop visible now. Use fingers on faders etc.
Another way: Get an iPad, iPhone or Android tablet or phone. Install rtpMIDI on main PC. Install any of the many Mackie emulators on the handheld. DAW Remote HD is nice on iOS. TouchDaw is nice on Android. Connect from handheld and configure Cubase for Mackie over the virtual port. There may be a Mackie emulator for PC, look around. Maybe use an android emulator on the PC to run TouchDAW?