I bought all the textbooks I was requested to, and to be honest I never really used them. Infact, half of the books I bought for 1st year didn't even get opened.
As for maths, it's suggested you get this big fat Calculus book for 1903 (or 1901, can't remember exactly). I got that, and I didn't even open it. Those lecture notes you can get at Co-Op should do you fine.
As for finding out textbook info in general; when your subs pop up on WebCT, you can download info sheets for most of your UoS which tells you there.