My opinion
Helmets- No (but let's not get onto that here)
High viz- No. The problem is largely not the (in)visibility of cyclists but lack of attention by drivers. Come and talk to me about high-viz once every motor vehicle on the road has been painted the colour of a Post-It note!
Banning headphones - They can have my headphones once every radio, CD player, mp3 player and the like has been removed from every motor vehicle in the land along with the soundproof seals which isolate drivers from the nasty world outside.
Primary position - Damn right, whenever necessary and Mr Toad tooting his horn behind me can f@%$ right off.
Highway code - A working knowledge of the relevant bits is not unreasonable for all road users but most of what you need to know is simply common sense and the, sadly highly visible, minority who ignore the code generally have none.
Flash or steady - I use both, back and front but see my point about high viz.
In general any measures aimed at cyclists are just fiddling around the edges until the main source of danger,i.e. poor driving is addressed.