I'd like to add another dimension to the question:
do the squads have to be dropped in the pod?
example: I have a tac squad in droppod and a dreadnought in droppod.
can I do the following:
deploy the tac squad with the army from beginning and call down the dread turn1. keeping the tac's pod in reserve?
can I deploy the tac squad and call down it's droppod on turn1 as a "sentry turret" with a bacon, keeping the dread in reserve?
this would make stuff liek thunderfires and devastors in pods extremely suefull to "play" with the droppod assoult-slots to either call down your whole army on turn1 (bare a few empthy 35p pods) or keep the more close and personal stuff in for true reserve.