please be more specific
A tricorn hat.
no they wear other color suits
the HASHASHIN did infact wear a type of uniform research on google for more info but your everyday assassin dont they are just normal people like you and i but, with some skill that others lack. They are just poeple.
when you get far in the campian you uncover a huge seceret and then u get to be a diffrent charecter who aventualy gets the outfit
A white one in Assassin Creed 2 and brotherhood and a black one in Revelations... They're like the one Jackie wears in Sleeping Dogs. You can buy it online.
On Uplay u can buy with some gamerscore u have achieved the regular clothes u wear in the beginning
they would there suits and other
Go to the city of Forli (you get there eventually in the storyline). Go to a tailor there and purchase "wetlands ebony", this will dye your outfit (mostly at least) black.
Once you put on the Assassin's out fit, that is the only one you can wear. You can change the colors of it at the tailors but you can't go back to the civilian outfits.
space suits
The same reason that Presidents, coaches, businessmen, and other people wear suits. It shows that you are a professional, respectable person. It is not a requirement in the Bible but an expectation of society.