I have installed in 2012 Photoshop CS6 on my PC with Nik Software plugs in. If I installed Photoshop and Lightroom CC on the same PC will one interfere with the other. Would my Nik Software Plugs in still work flawlessly?
Yes. Its fine to have both versions installed on your computer. A CS6 version can co-exist with a CC version without causing any trouble. Sometimes, you need both versions to be able to work with multiple clients and deliverables.
Although, if there ever comes a time where you wish to uninstall CC and run with CS6 only on the computer, then you might need to deactivate and reactivate CS6 in order to re-enable it after CC is uninstalled, and/or follow these instructions: