A complete map of Hydaelyn

[seekified]

Probably. As I recall most of the Garlean troops you run into in Eorzea are actually conscripts from Ala Mhigo and other imperial conquests. Given that most of those conquests are fairly recent, and thus unlikely to be very loyal to the Empire they can't really afford to spread themselves too thin or they'll start seeing multiple rebellions. Not to mention the logistics of sending an army that far.

Agreed. Securing Eorzea is likely a step in that plan, though - Vylbrand would be an excellent staging area for any voyage further west.