Hey this is my first post! On a old topic that might not ever been seen by you ISOMSWIM but other people searching might see this!
You can use a USB hub to stream all the cameras into a single USB line to your computer or another HUB.
Such as this one
Further more on question 2: I have no Clue im a programmer so I would make something to do soo. If you want me too ill make something that can display multiple webcam streams?
3: You have missed this response