UART bit-rate vs frequency fundamentals
I understood that a 2Mbps rate would be a fundamental frequency of
  2MHz


No, that is incorrect - in one period of 2 MHz there are two symbols. Hence, a baud rate of 2 Mbps might have a fundamental frequency of 1 MHz if all the data bits were 10101010101 etc..


  I understood that 16x Oversampling meant 16 samples per bit


That's what I understand it to mean.