Forum:KB:Source of the Imperial Army troopers

In Star Wars, did the Galactic Empire's Imperial Army actually have it's own foot soldiers separate from the Stormtrooper Corps, the Imperial Navy (particularly the Imperial Fleet Regiments with their legions of Imperial Navy troopers), Compforce, and the Planetary Security Forces?

First of all, Compforce, the paramilitary arm of the Commission for the Preservation of the New Order. Wny not assume that Compforce members served in the Imperial Navy, especially as Imperial Navy troopers, or in the Planetary Security Forces, basically to insure that the Imperial Navy and the Planetary Security Forces remained loyal to Palpatine and his New Order? Maybe the best of the Compforce troopers became Imperial Stormtroopers alone with Clone troopers, while the more mediocre Comforce soldiers served in the Imperial Navy and the Planetary Security Forces?

Second, is it to be assumed that the Imperial Army relied heavily upon the Stormtrooper Corps for it's foot soldiers much of the time? Maybe that in case the Army was short on Stormtroopers, it was forced to loan out Navy troopers from the Imperial Navy on a temporary basis?

Third, in case the Imperial Army was short on foot soldiers BOTH from the Stormtrooper Corps. AND the Imperial Navy, did it have the authority to draft the Planetary Security Forces from individual worlds, or even to hire private Mercenary units?