On the right side of the front picture of the helmet, the little part made with white foam is not parallel to the line which is on the upper part of the helmet.
I'm afraid that if I let it that way, it's could be very annoying when I will glue the visor, after the wood glue and paint steps.
Well, whatever you do, don't seal anything yet. If it's the piece I'm thinking about, the little part in the corner for the visor, correct? You might be able to hit it with some heat, or a support like a Popsicle stick or something to support it from the inside. You might need to separate it from the bottom and realign it, or in a worst case scenario you may have to redo the whole stupid part! But in my opinion it isn't as bad as I feel like you think it is.
And this is...the thighs ! I'm gonna add the straps later, just before applying the wood glue. Once the wood glue is dry, I will sand the armor pieces. I find it easier to sand foam when the edges are harder plus I can easily soften the hot glue excess.