A few discoveries looking in the ART files:

[dearmad]

PARADROP button art exists... no paradrop troops in game!


TRADE button (with wagon in the art) exists... but trade routes are autoestablished now. Hm.

There's an EXPOSE button (with pictures coming out of a dossier) so maybe spies could formerly expose other spies or units?

There was at one point a MINOR civ flag/thing, but it seems that Barbarians took over that role, I guess.

[ml_4da3]

See any throneroom art? I have seen lots of throneroom things in python and xml files, maybe its possible to reactivate someway if we have the art

[dearmad]

Heh. Haven't seen it yet, but there are a LOT of art files...

[Locutus]

I'm pretty sure Trade is to establish a trade route with a Great Merchant. Not 100% sure, but 95.

No, minor civs are still in, but for scenarios (always were intended as such). Check out Greek World, it has several minor civs, such as the Etruscans (basically they're Barbarians but with a colour, their own flag and a leader name, and they're slightly less aggresive I think -- but you can't do diplomacy with them (always war) and they don't build cities).