I'll answer what I know. But keep in mind this is only my second batch of chicks.
"crumbles" and chick starter, is the same thing. 80 degreees seems low unless your chicks are 4 weeks old.... I believe it starts out at 95 for day olds, and drops 5 degrees a week.... so four week olds would be at 80 degrees.
Mine are three weeks old, and are going outside in a few days. Do yours have feathers yet, or just fluff? I think if your lows are 55, and you have a sheltered spot out of the wind, you could probably put them out, with your light. Set your light up so that a thermometer in the box reads between 85-90 (since you aren't sure how old your chicks are). Then let your chicks tell you how they feel about that. if they group up right under the heat lamp, they're cold. Lower the lamp. If they all go towards the corners of the box (getting away from the light) raise the lamp. Your chicks should be scattered throughout the whole box.
My best advice would be to keep an eye on them if you put them outside. Make sure they seem content with the heat during the day... i.e. not too hot, and then go out well after dark and check again. If you have HOT days and cool nights, you may need to move the light up in the day, and down at night.
As for your "pasty butt", I had the same problem with many of my chicks last time (my first time). People on here told me to whipe it off as you have, and someone also told me to put a little smear of vaseline on their butts. I had to keep whiping them off for about a week, then they were fine. So I wouldnt worry too much about that.
Hope this helped some.