Actually Zulia's blue and white outfit the one that she is normally wearing is at a vendor in Desari Gardens Trading Post although I don't think that we are able to purchase the outfit yet. Also her wig is there as well. All you have to do is look at the general merchant there. You can view what your character will look like in it as long as your character can go to that merchant. Good luck making your character :)
Yes you can go back later and finish up any and all daily and side quests that you skip in lower level areas. I have done this since headstart last year. Just go ahead and do your yellows and you should be able to make the dead line for the outfit. Then go ahead and go back for the blues and side quests this is what I am doing with my nine characters to make sure that I can get the outfit on all of them.