I feel like I'm finally getting the hang of this game and I love it, but I still have several questions.
1) I realise that splitting pops makes RGO's much more profitable, but why? And what does the number by the RGO represent and what does it do when I expand it?
2) I'm not sure I get what organisation is or the use of brigades in the army.
3) What pop sizes make for the most efficient factory? What do clerks exactly do?
1) I forget the precise numbers, but the efficiency of 2 POP's always exceeds the efficiency of 1. The number by an RGO represents how efficient the province itself is with the good, to best represent how some areas were more productive then others. Expanding an RGO enables more POPs to fit in it.
2) Organisation is how quickly morale is regained, morale being the green bar during battles. If a unit runs out of morale, it is essentially taken out of the fight - unless other units have morale, in which case it is fodder for the enemy army. Organization is important especially if you want to reinforce your troops often, as that costs morale. Brigades -really- help units, as they not only add another 2,000 men to a unit, but also significantly improve the stats.
3) Bigger's better, quite frankly. I forget the specific efficiency to size ratios, but I think it's something like 1,000-5,000, 5,000-10,000, 10,000-25,000, etc. etc. Probably wrong, of course. Clerks significantly improve the efficiency of a factory - they're more useful than craftsmen since they also improve outright production, too. The ratio of craftsmen to clerks, however, has to be 3:2.