How to move price to the left and change button to rectangle shape

First, you should be using a child theme if your theme doesn’t allow you to add custom CSS. Using a child theme will allow you to do CSS customizations without them being overwritten every time you update your theme.

The CSS you need to move the price to the left is:

.single-product.woocommerce-page .product .summary .price {
  float:left;
}

To make the rounded button appear to be a rectangle, you’d need to change the border-radius property to zero:

.single-product.woocommerce-page .product .cart .single_add_to_cart_button {
  border-radius: 0px;
}