Question:
Flying a CAP mission or any mission in general may contain as many planes as the player wants as long as they are all flying to the same target hex, correct??

Answer:
Yes. But remember that not all the friendly air units in a particular hex need be part of the same mission force and that depending upon player choice, not all air units present need to participate in any one mission. For example, imagine a hex with 10 phasing fighters on CAP. The phasing player now flies a bombing mission to the hex with two bombers. The phasing player may switch any, all, or none of his CAP air units to escorts for that air mission. Note that this occurs before the nonphasing player flies any patrol attack or interception missions against the bombing mission.

Source:
TEM 59/60