I'm describing what I saw from many governments and comittees from when I used to review these specs for bidding.
I would have to disagree its not the norm, governments are always corrupted in some way, but thats a much more divergent discussion.
I can say with confidence that the overwhelming majority of specs are written to include or exclude specific bidders though. My work is and was global, too, so this isn't a US only issue.
How much they do to control the bidders list will vary though.
Nope, and I wouldn't recommend it either. They are generally not great with mapping IMO, no matter the model.
And really this is better managed with a quick diagram and a spreadsheet. If you want some software, look at netbox for this, you can add in validation rules and all kinds of automations as well.
But really, use a spreadsheet.