I haven't found anyone who has posted this yet but if it has been already posted a link to the topic would be greatly appreciated.

SOO... Once you enter the Cosplay contest with your avatar, can you change your HA afterwords without it affecting how it looks during voting?

Yup, once it's in, you're free to change all you want.

Dear goodness thank you! I cannot keep my HA the same for too long, it drives me insane! Thank you for answering my Question :)