Historically, if the FDA were to request additional information or trials it would occur during that 12 day acceptance of the application time frame; however, given that it is an external device and Arch is submitting, it would be unexpected.
With regard to the J&J talk- a brilliant Glaxo Smithkline manager told me long ago - if your product is going to be cannibalized, you want to become the cannibal.
Cheers and good luck.