Hello,
2. Unfortunately, it is no possible the first promo is configured in the Theme Settings > Shop > Header banner.
3. Sticky cart for a variable product has this view as a user should, first of all, choose the product variation and then add it to the cart.
4. You can configure the product page in the Theme Settigns > Product page, in addition, there is an option on the product page: https://xtemos.com/docs/woodmart/product-page-options/
If you want to rearrange the product page considerably, you will have to use a special plugin, for example, Toolset plugin: https://xtemos.com/docs/woodmart/faq-guides/building-custom-woocommerce-sites-with-toolset/
If you have any questions please feel free to contact us.
Best Regards