You should all really stop worrying, just because you end up living in a particular college it's not like they force you to spend all your free time there.
I don't think you have to choose 2nd semester courses then and there, but if you're doing actuarial then you don't have much of a choice anyway. Yes, you can choose something artsy.
Not for non-locals, read the booklet on enrolling. If you don't have a copy find it on the ANU site.
Classes start the week after O-Week, if that's what you were asking
Actually QLD does linear alg as well, it's not that hard. But I'd agree that unless you need 1115 for later courses, save yourself the hassle and do something easier.