On the first point, I cannot help you. As others have mentioned it was left unclear. I will say that they kind of left dangling about the other Gorn not in that system? Or were there other Gorn outside that system? What about Parnassus where the colony was. No Gorn left there? But what about all the hatchlings we saw in Part 1?
As to your second point, there was a line of dialogue on the bridge about the colonists being beamed aboard from the Gorn ship and being treated in secondary sick-bay. I know that from the time of TOS there has been discussion/debate/speculation that based upon the size of the Enterprise there must be more than one sickbay space.
I assume that based upon the possibility of a Gorn outbreak on the ship they cleared all non-essential personnel (aka, all but Christine and Spock) from main sickbay and relocated them to the secondary sickbay. You will notice that at the start of the episode there were patients in other bio-beds when Batel is awake and being given initial scans and treatment. But if that was the scenario, it might have added realism if they added a security detail to be there just in case of the Gorn bursting out.
Perhaps something was filmed and cut for time when they did the evacuation?
Cheers
[Edited for spelling and grammar]
