The part about calling 911 and saying unidentified men seem to be impersonating police is good, but don't try to talk to them or reason with them, that will just get you assaulted. They only care about subduing targets (to them you're a target or a threat, not a human). If they're already in your face giving you orders, hopefully a witness will make that call for you, and you do it for someone else if you witness it.
Except HSI and ICE don’t have badge numbers, so you’d say, “What’s your name and call sign?” The call sign is most commonly a letter followed by 3 digits. ex: A-123
Not accurate. If the goon squad is that close and questioning you or ordering you to do anything, you won't make it past the first sentence while they laugh and/or shoot.