1. ExpertHive uses WooCommerce for checkout and managing orders only. Unfortunately there’s no easy way to merge its account page with the WooCommerce one, but ExpertHive adds “My Orders” menu item and merges it automatically.
2. There’s no such option by default, but it’s possible with customizations, for example by overriding the “My Account” link via a child theme and displaying the current username instead of the “My Account” text.
3. Please let me know what details you mean, the buyer’s address or billing details? Sharing the buyer’s personal details to sellers may require some kind of permission or maybe it’s possible to resolve this via the WooCommerce “I agree to the terms of service…” option, you can require checking it via the WooCommerce settings.