Answering some of your points;
1) Registration – I guess you have checked that there is no boat number plate on the centreboard case – usually just aft of the thwart, and no sign of there having been one. It is possible that your boat was supplied without the copyright holders license fee being paid – and hence no plate. Hartley boats hold the copyright now – you could try contacting them to see if they will help.
If this is the case, you cannot get a Wayfarer sail number – unless Hartley’s will give you one.
2) Furling Jib: Discs are available to fit on the upper swivel to space the forestay away from the jib, or perhaps diy.
3) Rudder downhaul: always had mixed success with ours – sometimes an arm in the water is required.
4) Trailing – ratchet strap: if you are using a ratchet strap go easy on the tension, just take the slack out – otherwise the hull will be squashed. We just had the strap with no extra support with our plastic boat, but we are on wood now and use a strongback – a chunky piece of timber slightly wider that the boat which stops the boat being squashed.
Store the boom inside the boat.
We strap the mast to the boat transom- not the tailboard.
hope that helps