Since I didn't get a response here, I emailed tech support and here's the reply:

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There are no differences between the business and residential plans. They are the same package we just make it apparent that the service can be used for small business purposes.

If looking to have multiple adapters on one network you would need to ensure that traffic is being separated and distributed accordingly through your connected router. We can set up the 2nd adapter with different parameters so that this is easier to maintain but all in all that should not be a problem.

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