No.
No
Yes - but it well not be default. I am certain you are aware that all kinds of stories are spread about Manjaro - if the default was changed to accomodate your wish - it would just add another item to the FUD machine.
Because it allows for future signing of databases - without requiring several 100000s of users to change their pacman.conf - should it become important.
Answered by @Yochanan - it is the official way to keep up-to-date with 2 outstanding developoer applications (I have been a licensend user of Sublime Text predating my Manjaro usage) and supporting Sublime Merge was a nobrainer - it is better than any git gui I have previously used.
I have a very clear understanding of how and why this issue comes up from time to time as I have been troubleshooting the issue when I was a mirror provider. The troubleshooting process is documented in the following issue I created when investigating.