Hmm... I modeled these after real ancient greek armor pics, that do not actually have any spikes or fancy stuff, just plain thing, so I don't know if they need any. May be the helmet has a thing on its top, but I'm not so sure(my pics don't). I might model it separately and say it fell off
About plates - this one I'm sure there is none. Greeks had a single hammered plate for torso. And there will be no straps since armor is supposed to be old and rusted(not literally rusted, just oxidized bronze).
Abs - true, I'll work on that. Thickness - true, thanks a lot.

Anyway, I really appreciate your feedback.