1. Unfortunately, at the moment we don’t have those kind of feature. If in desktop with enable the small navigation when scrolling, i think we can do that.
2. Actually, at the moment when hovering the portfolio item, it only show the title and the categories. We don’t have feature to show the description of categories.
3. It’s weird for me. Anyway, can you create the example of those page and tell me which element that you want to show on desktop view and mobile view. So i can easily to help you.