Regarding Joel 2:32: The preceding verses make it clear that what is in view is a specific time in Joel's eschatological future, the "day of the Lord" (2:31).

Acts 2:21 and Rom. 10:13 are alluding to Joel and so are answered the same way.

In contrast, Micah refers to a specific upcoming temporal judgment against the people, and the word "cry" (za'aq, to shriek out of anguish or danger) does not mean "call upon."

Matthew 7:21 is not of any relevance to the OT verses and itself does not refer to the "Lord" in a titular sense as in Rom. 10:13. The word "Lord" here is kurios and is the normal title for any person in authority (like our "sir"). The people are recognizing Jesus' obvious authority but are not "calling on his name" -- they are, rather, calling out to him.