They are related to Vulcans but have evolved differently. Technically like more emotional Vulcans if I'm not mistaken.

actually, there is an explanation, but not in the movies. it's in the tie-in comic books.

romulans is exactly the same in this movie as in the rest of the star trek world. romulans stemmed from the same biological background as the vulcans, but they moved to a different planet a couple of thousand years ago and have evolved independently ever since. during that time, the vulcans developed the logic religion, while romulans keep to their ancestor's more violent and free-for-all ways.

actually, we dont see other romulans in this movie other than those on the narada (nero's ship).

the reason why nero looks very different is bcoz after their home planet destroyed in the future, nero and his crew went on a rampage. they killed the romulans high council bcoz they failed to stop the planet from being destroyed. they wiped out a fleet of klingon ships who're defending their turf. then they wanted to kill spock bcoz he also failed to save the planet. in doing so, nero became a rogue entity. they shaved their heads to purge themselves, and tattooed themselves to remind them of their lost. also, nero has a bite mark on his face, which he got on a klingon prison planet. this will be in the deleted scenes.

Watched it yesterday and like it. Overall I give 8/10. The main thing i dun like is Sylar as Spock ... It's just seems not right at all ...

i don't understand this part. how did scotty know that he needs to wait for future spoock and kirk on the ice planet?