unit sizes and gameplay

[Titus Marcellus Scato]

ok this is a question for the more experienced players out there regarding, the small, medium, large and huge unit sizes. What are the effects of these sizes on:
(I only play on huge to make it more epic)

1. Blitzing? - I notice that in a lot of pictures people post up in which they have conquered the world, they use smaller unit sizes like 80 men per unit. Does it make a difference? Ive always beeen curious about this since every single picture ive seen with a successful world conquest is on 80 men unit sizes

Blitzing is a little slower. Not a lot.

2. Battle Casaulties - less or more? Are the battles faster? slower? easier to control? I notice that in battles screen shots, the players using smaller units suffer 1% casualties when facing a full stack compared to like 5-10% i see from battles using huge unit sizes. will phalanx based armies suffer because they cover less space making the phalanx more easy to flank?

Battle casualties are higher on huge unit size, obviously, since both sides have more men. Battles are slower on huge. Larger units are more clumsy to maneuver (especially pike phalaxes) and become especially difficult in town streets (don't even bother taking a huge unit of chariots into town, it's not worth the trouble.) Huge units take longer to 'dress the line' after changing their facing. However, bigger armies are harder to flank. Easier to maintain a long, solid front line with no gaps (especially pike phalanxes.)

3. Economy - Do the smaller units cost less to train/maintain? And also since your unit takes away less of the population because its smaller does it increase the number of taxpaying citizens in your cities compared to a game with large unit sizes therefore making you richer in a game with smaller unit sizes?"

No, unit cost and upkeep is the same for any unit size.
Yes, small units take less population from your towns, so you have more tax income, and are a bit richer. And your towns grow faster due to less drain from recruiting, making you richer still.
I find that on huge unit size, hiring mercenaries becomes very attractive for all factions, because it is more economic in the long run to pay more up front for mercenaries than to stunt your town growth through heavy recruiting. On huge unit size, you really need to look after your town growth. Recruit first from towns that are losing population (since they are draining men anyway, might as well drain them into the army than lose them for no benefit at all.) Then recruit only from your largest cities that have high growth rates. Otherwise, hire as many mercs as you can. On smaller unit sizes, managing your towns becomes easier.

4. Is movement speed the same for armies?

Yes.

5. Will your game be faster? Are units routed more easily making the battles and the game quicker?

No, units are not routed more easily since morale depends on the percentage of men in the unit still on their feet, not just the actual number. That's why a heavily depleted unit which starts the battle with only a few men in it will still be able to fight until it suffers some losses, and won't just rout without ever engaging the enemy at all.