1) Ok, I understand, that he must start onboard.
2) I description of HMG crew is writen, that embarking or disembarking the Orca costs two actions. Not only one. But must spend this 2 actions not moving both HMG crew AND Orca, OR only HMG, there is difference between this two options.
3) You wrote, that HMG must spend action to form fireteam, but then You wrote, that after disembarking he act as separate model. So form fireteam os here only for purpose of joining another HMG crews from other Orcas and so one?