Squads or battalions for infantry units work really well together, because combining different specializations makes more sense than having separate units, in my opinion.

Nice ICBM shot.!

Listen, regarding the GitLab login—a lot of people are having these issues there right now, so don't worry, it's not just you. Regarding the attack move with control: yes, they tweaked the mechanics a bit in A27, and it's pissed off a lot of people who are used to sniping with Ctrl. Now the game seems to "prioritize" a target if you click nearby, and it's really annoying when units start acting up or rushing in the wrong direction. There's no real fix yet, and the developers seem to be aware of the issues, but that's just the way it is in the current build. Regarding the bug in "We are Legion"—it's a complete bummer; it sounds like a classic ID card conflict when loading a save. Since you can't submit a ticket, try their Discord or forums; the developers respond faster there than on GitLab—they're almost always online there.

Vanilla UI doesn't have space to display all unit action button, so it doesn't show it. You can use the hotkey as an alternative. I can also recommend using ModernGUI as others and myself contributed to fixing bugs and limitations of the game UI. There are at least 100+ bug fixs like this in the mod. You can also choose to wait a few decades  for them to be addressed in vanilla (no sarcasm, just a extrapolation of the time to get one item merged), staff and contributors do whatever they can to make it happen but the process is slow by nature.

Where? I see only six buttons: Self-Destruct, Abort, Attack, Garrison, Occupy Turret (which I don't know yet what it does) and Repair.