The only other question I have is the different companies and how that would work. I read the spoke and wheel blog mentioned in the links you shared. If I support multiple companies, I should just get a mini per operator license. Multiple viewers OR multiple licensing (2 free, 1 paid) does not seem to be supported. Would be a nice feature :)
Why, you can work from multiple Viewers. For example, if you have an operator license (standard or mini, regardless) you can install your license on as many Viewers as you need , provided that the number of Viewers you work from at a time does not exceed the # of licenses purchased. The simplest example is when you purchase a 1-operator license. It means that you can work from one Viewer workstation at a time, but you are not restricted to how many total workstations you can install (and use) the Viewer on.
As a consultant I come in to places that already have something like this and seems I would have to juggle around to use their address book and key.
None of the hosts require a "Key". Only the viewer. Any number of licensed viewers can connect to any host. You can use the same license key for all of your viewer machines. You are only limited to how many addresses you can have in your address book, by the type of license. Free = 10, Mini = 50, Per-Operator = Unlimited.
That, of course, needs to be done only if you enable the "Generate password automatically" during MSI Configuration and therefore have your connection credentials emailed to you in an encrypted message. If you don't use that feature, you can use the Viewer on another machine right away without copying anything - except perhaps your address book if this is how you choose to share it between machines (there are different ways).
With the free key am I just limited to one Viewer PC?
License type has nothing to do with this. The free license allows you absolutely everything that a paid license does, except only that with the free license you are limited to 10 PCs (records) in your address book.