Oh dear, there is a lot of misinformation on this thread (I'm a current student). The best place to find information is the Oxford admissions pages, as well as the individual college pages and the JCR (student) pages (just search "magdelen college oxford jcr" or similar). A few subjects, not sure which, will have a standardised procedure where candidates are interviewed automatically at multiple colleges, but for most, candidates are offered an interview (which for some subjects will be two or more actual sessions) at one college, with the understanding that they may be sent to another college (s) for further interview(s). Getting sent to another college doesn't necessarily mean that you won't end up at your first choice, though.
In terms of choosing a college, the idea of picking tutors with your interests is generally a fallacy. To begin with, your academic interests aged 17 or 18 are likely to change, or at least substantially develop, over the course of your degree. Secondly, when the courses start to specialise (generally in 2nd year for humanities, final project year for sciences), you get sent to whoever the expert is for that paper (module) for tutorials, whichever college they're at. Thirdly, whatever your interests at 18, the tutors are almost certain to have enough knowledge of it to talk about whatever it is you put on your personal statement - even a specialist in 20th century poetry will know enough about medieval English to teach the first year course. I merrily babbled all sorts of rubbish about what turned out to be tutor's specialism, and still got in.
The Norrington table is also, in my opinion, not something to worry too much about. Yes, they might be able to cherry pick applicants a little more - but if you're suited to Oxford, you'll still get a place even if they have to send you to a different college. Furthermore (and this is my own, admittedly unproven, hypothesis), those at the top of the Norrington table tend to be older, richer, colleges. Maybe they have better teaching, but mostly they have better resources. My own college hovers around the top of the table, and it is also very old and very rich. It has pots of money for all sorts of things, from travel grants to subsidised food in Hall to private therapy to random amounts of Amazon vouchers if you do well in mocks. All this means its students have less non-academic stresses compared to newer, poorer colleges, so will probably do better on exams. (disclaimer - "poorer" is a relative term, resources at pretty much any college are still pretty decent). That's my 2p worth anyway.
Generally, to choose a college, once DC have established it does their subject, the things to think about mostly relate to living environment. Is kitchen access important to them? Do they want to live in college accommodation for the whole degree? Do they like the look of big grounds, or modern buildings, or pretty little medieval quads? If real life open days are a thing again before your DC apply, I'd really recommend making a shortlist from the websites and going to see as many as possible. My own college just felt comfortable when I visited. Wherever you end up though, most people think their college is the best even if they didn't apply there.