Hi there! Thank you very much for your thorough review.
We are looking into the Add-on functionality issues while running Firefox Beta. At the moment, the Add-on was not built with Firefox Beta in mind. Thanks to the insights we received from you, we hope to solve these issues in the nearest future.
Regarding the default hyperlinking (issue no.2), users should be able to turn it off via toggle switch 'Set Blockchair as your default blockchain explorer' on the bottom of the Add-on window.
