[Theme: Sparkling] Few tweaks and problems

Hello, I have a couple of questions and I would really appreciate any help.
Site: http://www.speakingoftrading.com/login/

I’m using Colorlib’s Sparkling theme and I’m struggling with the following issues:
https://colorlib.com/wp/themes/sparkling/ (NO Child-Theme used!)

1. How can I change the homepage (just this page, not the entire site) to full-width in order to match the slider’s width (expand the container)?

2. How can I change the submenus colors and width? I would like to have the menu and submenus with the same size. Plus, when a submenu is created, the menu no longer accepts a link. Is there any way to turn it clickable again?

3. The search form displays random posts and site’s stuff when nothing is inserted into the form (when the magnifier is clicked). How can I prevent this behavior?

4. Initially the site had the structure of a blog, but when I changed it to display a static Front Page (with full-width (no sidebar) selected)), the site’s title and tagline (which can be found at “General Setting”) were replaced in the browser’s bar by the name of each page. Is there a way to always display that info again in the browser’s bar regardless of which page a person is in?

5. There are several forms available across the site, and they deliver error messages, info’s etc. The text in those messages was aligned in a box, justified. Now with the change mentioned above, the length of the boxes containing the text is no longer justified to match the text’s size, but is always aligned at the right of the page. What went wrong? I am not sure if what I mention is this: “Notifications” under https://colorlib.com/sparkling/sparkling-shortcodes/

Thanks 🙂