I would talk to the teacher and try to get a game plan that works for all 3 of you, especially your child.
I always volunteered in my kids classes and their seats were rarely in rows. They were placed in groups. Throughout the year their seating positions were rotated. That way, basically everybody had a turn sitting by everybody else. Also, when they worked on projects, there would be "stations". Scissor station, paint station, glue station, etc. It helped keep the supplies in one spot and the kids moved to them. Anyway, both the teachers and the children moved around quite a bit. In those instances, it would have been impossible to accomodate a parent's request for a child to sit in a particular area of the room at all times.
Like you said, this is something you wouldn't know if it hadn't been discussed with you so that's why you need to talk to the teacher. I don't know if it's realistic to expect that the teacher cannot move where your child sits without your prior permission. Especially if it's over something that might be just for the remainder of a day due to your child's talking in class. Your daughter is a normal child with hearing loss in one ear. That shouldn't mean she shouldn't have to move her seat for talking if that's the same thing the other kids have to do.
Another thing that I thought of was that because your daughter can't hear well, she may talk really loud. Not that she can help it. But it's something to consider and hopefully you and the teacher can work with her on it.
I really like the idea of the amplifier so that both she and the teacher can move about the classroom and your daughter can still hear her.
I don't think the teacher is "unwilling" to work with you. Better communication between you and the teacher is your best bet. Be sure to let her know you understand she has a class full of students and you're just hoping that she will work with you regarding your daughter's needs due to her medical condition. From all the many, many classes I've been in, I just don't know if it's logistically possible for your daughter to be right next to the teacher with a certain ear towards her 100% of the day or vice versa.
I hope you're able to get something worked out.
I know that as your daughter gets older, she may not like having to be right next to the teacher all the time. Those spots are usually reserved for the kids that are in trouble. :)
Every year, with new teachers and teaching styles, etc, you will have to go through the communication process so this is a good time to begin. You got really lucky with a kindergarten teacher who could do everything for your daughter that you asked.
Don't give up. Don't bite the teacher's head off. Work on a game plan together.
Best wishes.