Question about decklink video cards, audio sync and WireCast

Hello...new here.

I am currently running a simple streaming setup with an Intensity Shuttle: single camera and audio direct from mixing board (classical music streaming/higher education). I'm looking at expanding this system to include multiple-cameras but still only one audio source (of course).

Currently, I'm considering a custom PC with DeckLink video cards. With this setup, are there potential issues with audio synch (or even video sync) since none of these cards are locked together. I know in audio world, at a certain point, you have to run word clock to avoid sync issues. Is the same true here?

Also, I'm using WireCast as my software of choice for streaming. Would each of the channels of a DeckLink Duo 2 appear as independent channels in WireCast as viable video sources or would I have to have separate cards, such as the Mini Recorder in order to accomplish this? The 'soft' switching in WireCast would make things a lot easier...especially given 80%+ of what we are doing (c)would remain in this program.

Thanks for the help and advise.

Duo 2 should appear as separate inputs.