Poor old Stansted, it must be starting to feel a bit like a visitor centre, the number of potential ATCOs getting the guided tour recently [I just sent my cousin up there for a similar reason last month].
These questions are not designed to have a finite answer. They are designed as an opening gambit to assess your problem solving abilities. For every answer you give, you will then be fed another question referring to the solution you have proposed. This gives the interviewer an idea of how much thought you are putting in to your answers, and whether you are considering the ramifications of your solution, or simply taking a stab at a reasonable guess.
If you want a solution to the runway problem, try and think of one yourself, and then try and run through all the possible consequences of that solution. This will give you a better idea of what to do should you be asked a scenario based question which you have not previously encountered. They are testing HOW you solve a problem, not whether you can learn a trick from a book [or website].
Atlantic tracks are covered widely in literature, and should be pretty easily researched. The tracks are published daily, and follow tracks across teh Atlantic based roughly on Great Circles, but placed so as to either gain benefit from [in one direction] or avoid [in the other] any Jetstream activity over the Atlantic.
Approach sequencing is the technical term for the particular brand of voodoo exercised by Approach Radar controllers in order to achieve maximum runway utilisation, [or most aircraft landing per hour.] They do this by putting the arriving aircraft into the correct order, correctly spaced according to either the minimum radar separation, or the spacing required to allow for Wake Vortex [don't mention this unless you can field supplementary questions on it] following the preceding aircraft.
These are pretty simplified answers. be aware that ANYTHING you bring up in answer to one question, they will likely quiz you about, to see how deeply you have researched your subject. They will eventually hit the bottom of your knowledge on a subject, so don't be phased if they end up asking you questions which sound like ancient Greek. It happens to everyone. Stay calm, think before you speak, and be ready to admit that you don't know something, rather than guessing.
Oh, and enjoy it.
