Personally I'm not too fussed about the last two points; there are only a few core courses in Oxford's second year and they're all pretty fundamental.
I think they should be publicly available from this link:
https://www.maths.ox.ac.uk/notices/exam-reports/external-examiner-reports/2013I imagine there are some opportunities available for those who really go out and seek them. I do know a few people at or near the very top of their year and nothing special really happens to them. I've always idly wondered if we don't push our top students enough, and I think a large part of that might be lack of institutional support. Especially at parts B and C, when the department is just about entirely responsible for your education. I would cite the limit of 5 courses per term (for context, one does 8 courses for exam), the inability to sit extra papers, and the inability to sit papers from higher years as three examples of restrictions which I don't like (even though they are perfectly standard and reasonable, mind).
While I'm on the topic of completely minor and inconsequential gripes (
I love you really, Oxford) there's something that's always bothered me a little. The department as a whole and many lecturers individually encourage students to read from third-party sources, but from what I've seen few students do, preferring instead to just work from the course notes. Speculating here, a reason for that might be that other expositions of the material won't be that useful in light of exams. A third-party exposition is likely to go via a different route than the lecture notes, probably relying on different theory. However, for exams, you basically need to learn the theory exactly as presented in the lecture course, because I think few people would dare to cite theorems from outside the course on an exam. This leads to every paper having the same regurgitated proofs of bookwork, something complained about in examiners reports.
As a concrete example, suppose you're a fresher doing real analysis, and you're confused about the proof that a continuous function on a closed bounded interval is bounded and attains its bounds. The proof presented in prelims is by contradiction: construct a sequence (x_i) from [a, b] such that f(x_i) is unbounded, find a convergent subsequence (x_k), note that f(x_k) converges, and you've got your contradiction (since we assumed it was unbounded) (it's remarkable how much easier it is for me to construct this proof now compared to the difficulties I had as a fresher! One of those times when you look back and appreciate how far you've come). Anyway, I found this proof (and still do, to be honest) to be opaque and confusing. Suppose you go to a textbook looking for some more explanation and you find a discussion of compactness. After a while studying it, you say aha! It is all clear! f([a, b]) is compact and so closed and bounded! But then you sit and reflect: you can't really cite this on your problem sheets, and you certainly don't want to start talking about compactness on the exam, out of fear you will lose some or all marks for using theory from beyond the course. In fact, you realize, the time you spent struggling with a textbook was entirely wasted; this was useless to you (from your perspective)! You resolve not to do this again and just stick to the notes.
If I had to guess, that is what I would blame for our generation's ever-decreasing reliance on textbooks: the perception that they won't be helpful for the exam.