I was thinking of asking the same questions.
Having looked at these questions in some detail I think a) is easiest to answer with reference to the regulations (it doesn't help that the link in the draft NPPG seems to be broken) - http://www.legislation.gov.uk/uksi/2016/105/contents/made
Section 5 is the critical bit as we are required to collect date of birth, nationality and that they are seeking a plot for their main or sole residence. This goes a bit further than the draft NPPG text which say people have to be over 18 and a British, EEC or Swiss national.
That is all relatively straight forward but oneconcern I have is the bit that it says the applications have to be recieved in writing (and also that we have to respond in writing). I'm assuming it's fine to do this electronically but there doesn't seem to be anything in the regs or the act to say so.
As to what would make sense to collect I've looked at a number of the vanguard authorities - Cherwell, Shropshire, Teignbridge, West Lindsay, Exmoor, Dartmoor, Sheffield, Stoke on Trent, South Norfolk, Pendle and South Cambridgeshire. They all seem to be collecting similar information. I suggest reviewing a few and going from there.
