Maybe paranoid schizophrenics in the US tend to think the CIA is after them, but those in Soviet Russia used to think the KGB was?

It seems almost certain. In the least one should know about CIA's existence to have that sort of delusion.

Also, does Capgras delusion apply to everyone the patient has an emotional reaction to, or just their spouse/parents? If you were a very political person, and felt great pride/joy when looking at your favored political leader, and then you got Capgras delusion, would you assume they were replaced by aliens? What about your teachers, doctors, and friends?

This is a great question to test the emotional reaction hypothesis. I would add: what about their enemies? A negative emotional response is still an emotional response (well, maybe, I wouldn't be so surprised if negative and positive emotions were each associated with a different part of the brain).