Thr CMs must check each resort ID AND place the bracelet on the wrist of the guest, so the answer is no, one person cannot get multiple wrist bands even if they have the IDs.
You can arrive as late as (or maybe later than, but we did see signs saying wristbands would be handed out until) one hour before the park closes during EMH. (in other words if the park normally closes at midnight, EHM is till 3am, and you can arrive up till 2 am or later).