At DS's school they do their EPQ during year 12 and the unmoderated score is given to them in September of yr 13 with the actual results coming out in January. There are apparently 2 submission dates per academic year so it will depend which date the school/6th form submits on as to when they get actual results. some submit in year 12 and some in year 13.
DS is hoping to apply to Oxford to read history so is doing his on a history based subject that does not form part of his A level studies. Although Oxbridge does not necessarily require an EPQ sometimes the subject matter of the EPQ will be discussed at interview.
At DS's school the EPQ must be a formal written dissertation style report followed by a presentation of their report whereas at a local 6th Form they can do films, cook books etc. and it is presnted by holding an EPQ Fayre where they have a stall and can explain it to people who are interested on a more informal basis.
As regards "Admin": the student is marked on how they approach the process as well as the actual report (which I think only accounts for 25% of the marks I think). So they will get marks for planning, explaining what decisions they made along the way, how they found their sources and how they decide whether a source is credible or reliable, whether they did any independent research or surveys, what skills they learned along the way (eg. referencing, powerpoint, use of footnotes) etc and so on. If you look at the syllabus for the board they are taking it gives a breakdown of what marks they get for each area.
They are marked and then moderated internally and then also moderated by the exam board. The reason why many people seem to get A*-B for their EPQ is that they have the choice to submit it or not after it has been marked and sometimes if it is a lower grade a student would rather not submit it and then it will not appear on their UCAS form.
Most grade offers that take EPQ into account are looking for at least an A.
DS did an HPQ alongside his GCSEs (which is the gcse equivalent) and found it useful and interesting as they can literally do it on whatever they want although the advice at his school (I emphasise at HIS school as I know it does not need to be the case) is to link it to the subject you would like to do your degree in to evidence your interest in that subject, assuming they already know what degree they want to do, which I appreciate isn't always/usually the case in year 12!
Having been through HPQ and now an EPQ feel free to ask questions.