Valid points, for the most part, if you're that upset about historical accuracy in entertainment. I nit, though:
There isn't much evidence that any Greeks except for Spartans fought in that battle. On the first day, the phalanx held, and Spartans were refreshed after each wave. No other greeks are noted to have been cycled into the Phalanx.
The Phocians withdrew from cowardice and never fought.
The 300 then fought a tactical retread while the rest of the forces made withdrawal in small, stealthy groups so as to not alert the scouts of Xerxes.
By the 3rd day, there were only 300 Spartans and 700 Thespians. Once the 300 were dead and the Persians took the ground, the Thespians surrendered without a fight.
Of course, it was but half of the bigger picture with the Athenian navy under Themistocles, the brains behind the operation, but the movie never pretended to be anything than a fantasized retelling of the battle at Thermopylae.
Reading reviews, however, it seems people are reading themselves into the movie. Some find it homoerotic. Others find it homophobic. Some find it neo-con. Some find it bleeding-heart liberal. Some find it fascist. Others counter by pointing out the dialogue is utterly anti-fascist. Some people claim to find parallels is Xerxes/Bush. Others claim to find synchronicity between Leonidas/Bush. It seems people are bringing their own interpretations into the movie and reading them into the story
But all of the info you've presented so far was in the documentary on Discovery the other night. Is this where you're getting your info? Much of what they presented is, well, rather contested and not exactly agreed upon by the historical community