How to play Alexander?

[cseanny]

so with a dedicated specialist economy cottages are a no no?

Not at all. It's map and user dependent, i.e., personal style (I'm just stubborn!). Some maps might only have one good city site that has any rivers or luxuries at all so be flexible.

 

[JustBen]

Aggressive to get units higher up the combat tree ... I don't tend to pick leaders with the war traits but I wanted a little change as well.

There's nothing wrong with trying to craft a strategy around the military traits for its own sake, but they are generally accepted as weaker traits. If you just want to fool around with highly promoted units, Charismatic does that with an econ perk that is pretty useful in the early game. Prot, Imp, and Agg are more for variety than strength. To be fair, the variety is well implemented. The trait discussion for the Deity Always War series on this forum confirms that, if you want to read (a lot!) more.