Thanks for choosing GP!
1. No reason to stop using BB and use Sections – it’s totally up to what you need vs what you don’t need. Page builders like BB offer tons of stuff that Sections don’t. Sections are very simple, so if you don’t need all of the widgets/extra functions of BB, then they’re awesome.
2. Disable Elements only work on static pages – this is a limitation in WordPress. However, there’s some very simple CSS you can use to disable elements. If you want to let me know which elements you want to disable, I can provide the CSS.
Not sure what you mean by contained? Which elements?
The spacing between the content and sidebar is controlled by the separating space. Or are you using the “One container” option so there’s no separating space?
3. You can insert elements into specific categories like sliders using GP Hooks. For example: https://generatepress.com/forums/topic/page-header-addon-not-working-on-woocommerce-pages/page/2/#post-165475
Your site is looking awesome! 🙂