The first issue IMO depends on the application that generates the notification itself, so I'm not sure if there is anything to do about it.
The second issue: I'm assuming you are using Evolution, but if you are using something different, just use the corresponding .desktop file for that email
You could copy the desktop file from
The short answer is, no. You can't get necessarily get elementary OS versions of packages faster than they are released.
Selected packages for eOS are designed to be stable, and as such, if you want packages before release on eOS, you might need to be prepared to use unsupported packages, and they may or may not work as intended (although often you will be ...