I'm solidifying my vote of Jabo on #1. (Edit: but I'm already wobbling again. someone else might still recognize it as an older swirl. Wait for another opinion.)
I don't remember hearing of a Vitro Unique. For sure put that one in your Conqueror pile.
Seams are a big help in identifying maker. However, it's not straightforward. Long seams could point to Akro, Vitro, Marble King. Short seams could point to Master or Foreign. There's crossover. If the marbles have ribbons to go with the seams, how the ribbons come together at the seams is a big help in making ID's. And base glass and other glass colors get taken into consideration.
More about Uniques -- it's a misunderstood name. I think it was thought to be an early Akro patch. But then more research has shown that it may have been a later Akro name, for a marble which was known by another name earlier. And it may have crossed over and become a Master name. But the type of marble which belongs to it -- highly in doubt. Unique boxes may have been filled with different types of marbles. But I only remember Akro and Master being associated with it. Basically, Unique is not a name which I have ever given to a marble when identifying it. There always seems to be another name which more readily applies, or there seems to be doubt about whether the marble has a name at all. Unique pretty much never comes into it, unless you're looking at a box specially labelled Unique, and then it's "Wow -- look at the surprising marbles in that box."