I’m pretty sure Rod’s titan’s face and front of his torso were like that because they were dragged along the ground? i could be wrong but i think i remember them showing a face when he transformed
Yes it does and he is also neglecting to mention that Rod. Said he should under no circumstances become a titan. He is getting the reason from one statement from Kenny. Problem is it is inconsistent with everything else. Primarily that abnormals happen when injected normally still. So we have no reason to think Rod would have been a normal pure titan and he implies that he knows him becoming a Titan would be bad and only does so at last resort. It's completely possible that a royal holding the founder could know how a person will turn out as a pure titan.
The story tells you who she is. She is Dina, a woman of “royal blood” turned into a titan in front of grisha Yeager. She is controlled by the founding titan power when eren is able to use it, and he sent her to kill his mother so that the story events could happen the way that they did. Sentient? No. Human? Yes. But is controlled by the founding titan, as all titans are, and can be controlled by the founding titan.
Carla death was meaningful for the fact eren said he had to make the smiling titan eat his mom so that young eren had the drive to get rid of all titans.