The trailer is definitely awesome, but these days trailers are theatrical productions in themselves (like music videos). It's entirely possible that ALL the decent scenes in a 2 1/2 hour movie be squeezed into a 45 second trailer, as long as they are a ) put in out of sequence; b ) made to flash across the screen in quasi-subliminal fashion; and c ) accompanied by suitable mood music. Case in point? The Dungeons and Dragons movie (the WORST movie I'd seen in a while).

That said, this does look half-decent, and I'll be looking forward to watching it.

I dont think so, I think this movie is really gonna surprise a lot of people who aren't expecting much.

I don't think the went onto the battle field naked, though I'm not positive. Your friend may have been thinking about wrestling in the original Olympics, which was indeed totally nude.
I know Roman custom (which took a lot of ideas from Spartan) was to wear armor of some fashion, so I would think that Spartans would be of similar ideal. Not to mention the hoplites wouldn't be very effective nude. Course, I might be totally off the mark, so it may be one of those things you want to look up.