okay i dont know if its been asked, but what is with the lightbuld helmuts i would be very scared if i had to be in one those on a hostile planet and i was thrown against a terrain that was rocky or could shatter the helmut there seems to be no protection and second what are they going with is in the past before first contact or in the future when the relays was blown up yes i know they could rebuild them thats a given but i wouldreally like to know ore indepth of the lore concerning this chapter of mass effect...
But i love how its looking overall
I don't think the helmets look that much smaller or less robust than the standard N7 helmet Shepard used, unless you're referring to something else than N7 Guy's helmet in the E3 trailer and concept art. And as long as we get actual helmets for everyone, I wouldn't even care that much how lightly built they seem 
As for timeline, we don't know for sure, but I think it's safe to say it's not before first contact (assuming you're thinking of our first contact) since we have humans mingling with the other species
hopefully we'll know more soon! Brain fart. Timeline is after the trilogy, as the post below reminded me...