You have a point here, but Odo is a very rigid character, and making him do something like assassinate a Romulan senator doesn't fit with his character, regardless of moral standing. You already said it'd be very difficult to write. Well, yeah, that's because it doesn't fit with him.
Eh, at this point maybe we can agree to disagree. But I give you this first:
"There's something else the other Odo wanted you to know, he was responsible for changing the Defiant's flight plan."
"Why?"
"So that you wouldn't have to die."
"I can't believe it! Eight thousand people!"
"He did it for you, Nerys, he loved you."
"That makes it right?!?"
"I don't know. He thought so."
But there's no overacting in the episode you mentioned aside from the aforementioned "It's a fake!".
Sisko's monologue to the camera counts as overacting in my book. I actually liked "It's a fake!", it was funny.
Damar is a better character than either Spock or Picard. And how well the character is remembered overall doesn't say anything about the quality of said character.
Maybe, but you do understand that you are in a very small minority with this? To me it is inconceivable that someone would prefer Demar to Picard.