1. ROC is probably linked with Yunru as members of Foehn. American rebels will probably meet with Foehn in next Foehn missions, but Europeans? Foehn doesn't have any way to find them, they're not humanoid Drillers.
2. Because Rashidi and Yunru hate it.
The faction with the least numbers of troops hates cloning? Despite facing a war which will decide the fate of humanity forever?
There should have been Covert Ops missions in which the Allies steal Cloning tech (Act 1 right after Chicago) and later the Soviets (early in Act 2)
The ability to multiply the army over a dozen times is the second-most powerful technology in the Red Alert Universe. First is mind-control
Foehn should have lots of Terror Drones and Robot Tanks in later missions. Maybe have their entire army immune to basic mind-control in the campaign