Yes, currently they arch their backs a bit (like a āCā), which I imagine is quite tiresome. The men should stand upright (like an āIā):
Indeed, structures are not to scale, nor should they be; maps in 0 A.D. are much too small for that. I doubt even a giant map would reach a kilometre across. On the other hand, rabbits are disproportionally large, which is fine, they're already difficult enough to see when zoomed out. So no, I'm certainly not arguing everything should be of one and the same scale.
However, the differents parts of an entity ought to be about proportional; capes and shields are on the same scale as the men, for good reason; in my opinion pikes out to be relative to that too. In reality pikes were about two to three times as long as thrusting spears, or four to six times the length of javelins. Part of 0 A.D. is educational, and having more accurate pike lengths won't hurt. It's in small details the game can really shine.
Indeed! Or differentiate factions; e.g. Iphicrates' peltasts a 10-cubit pike, Alexander's phalangites 12-cubit pike, Seleucid's a 16-cubit pike, Ptolemies a 14-cubit pike. Moreover, having properly long pikes would allow mods to experiment with the syntagma.