Can political issues between Iran and USA affect me?
I think that as far as paperwork goes, your Australian citizenship will ensure you have very little trouble. 

Regarding racism, I think the point that Boaty made above was that your explanation about your being Iranian but Bahai will really not change people's attitude or conduct towards you. Reason does not work with racists or bigots.

On the positive side, you will find many people (especially in academic contexts) who will be welcoming and non-judgmental. 

The extent and frequency of the racism that you experience will partly be a function of how identifiable you are as a minority. If you have a skin color that lets you "pass", do not have a beard and so on, you will attract less of it. 

Similarly, geography is an important variable too: If you are in a small town in the middle of Idaho, you are obviously more likely to be treated with suspicion and hostility than in Berkeley, CA. 

Overall, my advice would be to not worry about it and have a great time.