Exact answers to your question can be provided by google authority. But let me try to share my findings regarding your questions.
a) I did not find such information in googleplay policy here and here . But in this link in one place it is written that
Assets must refer to the same logo and icon that users actually find in the All Apps launcher after they download the application
So, we can conclude that it is necessary to use the same icon. Although I do not know how they check it.
b) While there is a way to do this. No information, like name, description, images, can be set differently for different languages ββ(someone corrects me if I am mistaken). You can do one thing. For different languages, you can publish different apks with a different package name. When searching, you may find similar problems. this is so the question is one of them.
You can also check out Support for multiple APKs on Google Play. Although it is designed for different devices, you can check whether the same actions can be performed for different languages. (I'm not sure about that: S)
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