Response to an unknown guest
Probably. Harriet has blind loyalty that ties into her anger. If her anger shifted from her enemy to Krell (or in this case Ironwood), I think she would break down.
I think Rex and Fives would speak out, but not as passionately as Marrow. When Rex confronted Krell, he still had his soldier behavior, but laced with some malice. "It's Captain, sir." The only way I could see the 501st betraying Ironwood is if he had them kill each other. Not like an execution, but I mean unknowingly shooting each other.
Response to ARC-5597
That's a good question. Usually when characters need to be redeemed, they realize what they did was wrong. I haven't seen any of that from Emerald, she was just scared of Salem. But I don't think that matters now, she's here to stay. But with Cinder, I could see it going one of two ways:
1. Cinder tries to manipulate Emerald into coming back to her, but Emerald realizes Mercury was right.
2. Cinder gets pissed and tries to kill Emerald, and Emerald realizes Mercury was right.
With the way the show has been with Cinder, I could see her going the second way.