@Bramborough Nice review. Regarding garrison armies, I would advise you to not park armies in the cities unless they are vulnerable to attack(borders). You can increase public order by other means, such as edicts, lower taxation, etc. I play the Julia campaign, and actually right now I have only one army in all of Italy(which I will be using for the invasion of Gaul in a few turns), even the cities to the north like Velathari and Ariminum are quite unguarded, as I haven't gone into war with Helvetti tribes in the north yet. So you need not park an army in every city that you capture.

One thing I discovered is that the cash flow at the start of the campaign is quite low so you will have to watch where you are spending that money. But as you progress through the turns and capture more cities, get trade agreements etc, your income increases considerably.