Co-op has all the textbooks for UTS subjects. Go to 'book search' then 'text list search' and work your way from there. Books that are listed as Status: text are required, and Status: Recommended are, obviously, recommended. You'll probably use this site, in the very least, to find out what books you'll need each semester, so bookmark it or remember it or something. In your first lecture for each class, they will also hand out a textbook list, so you aren't expected to have them for the first class (though to avoid the rush, some people do like to buy them early).
If I had to guess, it looks like UTS has given Co-op the subject details, but no list of books (whereas other subjects will simply say there are no books). Web Systems did not have a book when I did it in 2008, nor did Chris Wong's other class I have taken, so I very much doubt there will be one this year. Just looks like a communications error, is all. If you're worried, just wait until week one to see if he has assigned any books for the subject-- knowing Chris, it's unlikely you'll have to purchase anything.
Yes, textbooks are needed for electives if the elective requires a text-book. Treat electives as you would any other class. Check the Co-op Bookshop for the texts, or get the list in class, then buy the required ones =D
You have been searching correctly-- as I mentioned previously, there are a good few IT subjects where books are not required, simply because the information is easily available online and a text-book would be redundant. However, these subjects still tend to have a recommended reading list (which could easily total $300/subject), but they're not core subject material, and most are available for loan at the library. Most coordinators do not put the recommended reading list on Co-op Bookshop, since it tends to confuse students, but when they hand out the subject outline in class on the first day, they'll all be listed there.
Lecturers couldn't care less .. you're the one who's going to need to use it.
You don't need to buy anything. If you somehow can learn it without the textbook I don't think they care at all.
What happens when they do 'textbook readings?'
Not really, no. Some tutors will request you bring a book with you, but most are indifferent. I've not been in a class where you do readings-- they expect you to do that in your own time. Lectures are for lecturing (you'll take notes) and tutorials are for practical work (mostly). I find myself consulting the book in tutorials often, but that's because I don't tend to read anything at home. So, no, if a tutor said "now get out your book because we'll be reading pages..." I'd get up and walk out. Not worth the $900 you're paying so they can hold your hand while you read.
It really doesn't take long. Enrolment day is difficult, because the system (both the actual computer system-- which is complex in and of itself, but also the way subjects work-- what to enrol in, when you should be taking subjects, etc) is new to you. You'll quickly get the hang of how uni works, and next year, when you have to enrol all by yourself, you should be able to do it almost competently. Outside of that, getting to classes and dealing with big lectures where a lot of information is covered in a short amount of time can take some getting used to compared to the hand-holding of high school, but it's not such a huge transition. It'll be second nature to you in a few weeks, for sure.
Each lecturer will hand out a subject outline in the first week (unless they're lazy) that lists the required and recommended books for that subject-- so you'll receive one list per subject. If you're not wanting to wait until the first/second/third week to buy books (The book-store is packed after first week... 20-30 minutes just to get inside), use the Co-Op Bookshop text list to find out what books you need and buy them early. I've linked to it in another post in this thread, so take a look at some of my previous posts.