So I thought I had everything kosher on Drop Pods but it turns out I really don't know how to answer this question. Normally you can choose to send a Drop Pod down empty and have the contents walk onto the field. You can also bring down a Drop Pod and combat squad a unit of Marines inside as long as they exit from different sides (i.e. distinguish which marines are with with squad).
But...
Can you combat squad *BEFORE* the game starts and send only half the squad down? I know this is probably suicide as it drops the number of guys in the unit in half and arguably gives away a free kill point, but is it a valid tactic? I don't have my codex near by so I can't read it and I can't recall the FAQ addressing the issue either.