How can I remove the product image frame in the Dawn theme?

Hello,

Sorry to hear you faced with this kind of issue.

I hope I will help to fix it.

1.Solution for your 1st problem with border. you may find bellow:

Open “edit code” for your theme → find file “base.css” → paste code bellow in the end

.collection .card-wrapper .card.card--outline {
    border: none !important;
}

2.And about buttons. Do you want to go back to what it was like on screenshot bellow?

Or you want to change color of active variant which you have now? ( You are right, currently it is white).I made a screenshot with red active variant.