Pretty much done by many (if not most) players right off the start, why not make it the default (with an option to enable / disable it)
This could also help new players progress faster through the game by getting them more familiar with control groups
There are more things to be done right off the bat like queuing villagers, building houses and moving sheep under TC. They are all more important than your suggestion. But still I don’t feel any of that needs to be automated at the start. Assign control group to scout can be done while you are giving it its first commands without even taking up any time.
And this not worth having an option for. Options also have a cost: space on the options menu, need for testing, chance for bugs etc.
The initial scout can be initially selected with find idle military or select all military.
No, this is not true for all game modes like DM
Those are not related to my suggestion, everything you mentioned can be done in different ways, even queuing up villagers (one can do loom first if they choose to). There is only one way to set group 1 to scout
“Select all military” (usually multiple keys) + “Assign group” (usually multiple keys) VS pressing “1”, unless you are a bot this should take some time pressing the keys
Please check the options page, there are alot of options that one can consider far trivial than my suggestion.
There is plenty of space
Same for any other feature, except that this one should probably be easier to implement as the initial scout is already identified by the game at the start and given a unique “auto-scout” feature
Saving any time at the start of the game is very beneficial, specially in DM where the first few seconds can determine the game