I will offer up a rationale for the tac/tank combo. Think about Panzers and Stukas for a moment. The Panzers are used to pin down the enemy in known locations. Then Stukas are sent in to finish off enemy defensive positions before the Panzers blitz the line. If it weren’t for the Panzers pinning the enemy units, they would be harder for the Stukas to hit.
All of the Dutch “places” are islands, so no, you can’t build ICs on “Dutch places”, but only because they’re islands, not because they originally belonged to another country. For instance, both the Allies and Japan have the option of building an IC on French Indo-China if they gain control of that territory.