The transverse crest is found on non Spartian pictures too, it is very rare anyway. There is for example a coin from Messembria in Thrace showing a Corinthian helmet with transverse crest. Is it an officer's distinction? Most authors today say yes. But we have no ancient proof for that.
I would use only one per unit for that reason and other towns surely used other styles do denote an officer. Athen 3 feathers?
If you refer to the Hail Caesar rulebook you will see that the Peloponnesian War scenario presented there does include outrunners, i.e. ekdromoi, and represents that with a Short Range value of 3 rather than 3/0.
If your opponent is agreeable, this is fine way to go. My understanding is that Ekdromoi were lightly armoured and younger hoplitai who would run out to skirmish and/or disperse skirmishers. Therefore, they originate within the phalanx unit and do not need to be represented by a separate unit, though filling the middle or rear ranks with lightly armoured models may satisfy representational needs.
However, do note that use of Ekdromoi does not seem to be consistent across time or region. One probable reason is that their role was obviated or forgotten when peltasts became common components of armies. The Spartans used to use Ekdromoi it seems, but by the time of the clash with Iphikrates and his peltasts this no longer seems to be part of their SOP.
i) you are playing in the later Peloponnesian War period or after when Greeks, rather than Thracians or others, start serving as peltasts; ii) you use very lightly armoured (cloth) hoplitai; iii) sub a javelin for the spear; and, iv) of course, the smaller shield or crescent pelte.
It's a little tricky with the Warlord plastics as the arms are molded into the shields or else you could just simply sub another manufacturer's shields. Of course, there's the finicky strategy of shaving down the existing shields.
Yes. It really depends on the time period. Of course, the original Thracian peltast is a classic. The Warlord/Immortal Thracian models are quite nice.
Since I'm playing a later period I'm probably going for Old Glory since I need lots of peltasts cheap. Plastic peltasts would be great since it feels painful to dish out more for peltasts than heavy infantry hoplitai. Plus, historically they were used in great numbers.