you can do that :) - also join us on https://github.com/code-for-charity/YouTube-Extension

1. Miniplayer on the youtube homepage is a youtube feature, please check again?
2. should not happen, you dont have to click the extension icon usually, the site might only reload if you change something big like dark theme or video resolution
join us at https://github.com/code-for-charity/youtube-extension
(where we try to improve features and structure all the time. you might be surprised. if you post the issue there, chances are avolunteer will have a look, even if you are the only one asking ever.) we volunteer for this cause since 10 years for 500.000 users and 100+ features! (Please try to be fair in ratings)
many smiles!

Thanks :) For header hiding you might have run into an unknown bug? Meet us on Github to report details. Many smiles