Hello,

1. I think you mean integrate the titlebar into a top panel (I think the systemtray is the collection of notification/sound/etc). That is doable by installing a widget called Active Window control. To use it with a global menu you should install it from github. Beware that apparently it's a bit unmaintained now. An alternative is to use a combination of widgets called: https://store.kde.org/p/1274218/ , https://store.kde.org/p/1272871/ , https://store.kde.org/p/1274975/

2. There are lots of themes and there is also Kvantum theme engine which gives you even finer control of what something looks like. https://github.com/tsujan/Kvantum/tree/master/Kvantum . There are many great themes to choose (you can use GTK themes for the GTK programs and then other for QT ones. With Kvantum you have lots of options but it can be time consuming. Take a look at my post: https://old.reddit.com/r/unixporn/comme ... _one_gifs/ here.

3. You can change how the alt+Tab navigation looks under: Window Management -> Task Switcher, it's under the visualization column.