You could probably do this with all of the empires. Under Heth, I think the Caldari version would be rather USSR-ish. The Minmatar version might be something between a riot and a street party. Or both. But I think all of that depends on how much the "PR" people are in charge. Any professional soldier is going to want as many chances as he can get to kill the other guy before he even knows he's there, unless they are deliberately trying to make the other side surrender with shock and awe. So, I think it more likely that all the big displays would be after they've captured the town, not before or during.
On a point Esna brought up though, if you want propoganda in FW space, why not use cans as beacons? After you capture a system, have someone drop a can off saying "Amarr rule, Minies drool," or whatever. Might be a fun touch to use.
Actually, I think progaganda would be HUGE in both major wars (Amarr vs Minmatar, Fed vs. Caldari). I think it would be used before, during, after, etc. Heck, even the players use propaganda to drive the wars, even when they arent even aware of it (ex: "Fed tried to commit genocide on us!" "we're here to better you, look at the slums of Rens and tell us youre living better!" "we come for our People! (most whom prolly dont want to give up their faith)" "join the Fed and live better in the shining beacon of freedom!" etc)
The dirty secret about EVE's big wars is that in fact they're actually long running civil wars, spanning centuries, between peoples that were at least nominally once under the same regime. (yes, the entire Minmatar pop wasnt conquored, but the Vindication Wars were very much a civil war between two factions of the same people, i.e. Ammatar vs. Minmatar).
In civil war, or indeed any war, controlling the narrative is HUGE. If you lose the narrative, youre well on your way to losing the war. You're fighting for your version of your story as much as you are for territory, mental mindspace is the area youre ultimately trying to conqueor, etc. This is especially true when youre in a clash of ideologies between people who share much the same history.