As I think you've twigged, there's a lot of details that don't come off too well because you run into game mechanics limitations. I find in Alex I rarely get much beyond Sardis or Gordion with my original Alexander, never mind establish Alexandria Eschate The 'one year per turn' one is the biggest obstacle to anyhting like historicity, so although you can have geographically faithful campaigns (quelling the Greeks, Illyrians and Thracians as you already have done) there's no real hope of temporal fidelity.

And the naval side is still bit of a problem - I've turned down the ship-building preferences by a factor of ten in Alex, but the Persians still bleed themselves dry with their navy Who said Phoenicians drive a hard bargain

So in the next release - which will be the "ATW2 Eastern Empires" package - after I've finished the Rise of Persia scenario - I will institute a land-bridge in the Hellespont, and have a few border tweaks around that area on the campaign map. I think the Punic campaign might benefit from some naval tweaks as well - thinking of adding a new ship type - the Lemboi - available only along the Dalmatian coast, to help the Romans out a bit.

As for the starting age of kings, you have no choice at all, all starting kings will all be somewhere between 30 and 40 years old (kinda limits it for Alex the Whippersnapper....), and the factions' biasses for acumen etc seem to be either randomised or somehow dependent on the king. To some extent you can address this by adding some heroes so that a few good governor candidates can be guaranteed, but heroes can be a bit over-powering as well if you over-do them. Anyway, the Carthaginians can afford a few dimwits, they have by far the best economic potential

Glad you enjoyed your Sicilian campaign - the Syracusans are meant to be tough (and are a great faction to play as, one of my favourites...) I wonder did you assault the stronghold? It's one of the ones that has a (reasonably) accurate portrayal of the actual defences, within MTW limits (the other one is Carthage). Syracuse is a particularly bloody assault, and I often fail to take it as an assaulter.

Start dates - Punic begins five years before the First War to allow the Sicilian tension to build, Alex begins in his historical ascension year, and there's another bugbear - you can't "recalibrate" the dates to show the date you want.