The main issue was the StatusBar plugin I used, which caused the weird layout. After removing it, the layout was fine again.
As to the status bar - I don't really need to control it during the app so I did the following: Open the plist file (Resources/{ProjectName}-Info.plist) and add the key "View controller-based status bar appearance", set it to "NO". Also create the key / make sure that "Status bar is initially hidden" is set to "YES".