Hi Thomas,
Neither of these customizations are recommended, and we cannot help much with them, but here is some general advice:
The first thing to point out is that the End Date is actually required for events to function properly. If you truly don’t want this in your back-end event views, it’s a very extensive customization far beyond the scope of support here – you’d have to remove the checkbox, but then rewrite other parts of the plugin that rely on there being an end date for an event.
As for removing the “All Day” event checkbox, you should be able to hide this by removing the table row element for this field in src/admin-views/events-meta-box.php.
This is NOT recommended, because it requires editing core plugin code, but that’s how to do it if you’re interested 🙂
Cheers,
George