>>2220883
SMAC is mechanically the same as Civ 2 using its improved engine. Almost everything from teching to building and growing and improving the tile is the same as in Civ 2 discounting extra features which are built on top of the basics.

C2P and EL basic mechanics are different from Civ 2. Simple as.

>It doesn't matter if they are useful, you MUST get them to unlock next era.
If you beeline communism and ignore rifling in Civ 4, which you can, you'll get stomped by unfriendly AIs that will see huge power discrepancy, meaning that not everything you can do, you should.

>Maybe because for starters, republic was kinda meh in 2 and you are probably confusing it with democracy from 2?
Are you serious? Republic in Civ 2 was "meh"? The fuck are you about?

>Industrial era specialists completely change the city micro (not to mention making it viable due to having now removed pop limit)
Do you mean policemen and engineers? Which were added in Conquests which you hate so much? What a clown.

>>2220886
>Except for non-resource units, in particular the medieval infantry
Medieval infantry literally requires iron to build. Have you even played Civ 3?

>>2220889
>Defensive bombardment is already in the final patch of pre-expansions 3.
Stop talking shit out of your ass. Defensive bombardment is added in the editor by adding non-zero value to rate of fire and bombard strength, and leaving bombard range at 0. This way a unit can bombard defensively as any regular artillery, but cannot bombard neighboring tiles. You can add this yourself at vanilla Civ 3 without patches, they simply didn't until Conquests.