Let's just say that the rules are more like moral guidelines.
- It's not a race - it's highly unlikely that anybody would be mad enough to complete the entire network and, even if they did, they're not likely to take the same route, so competing against others is pretty pointless.
- It doesn't have to be done all in one go - apart from the huge distances involved, most people couldn't spare the required time in one lump, so I predict most people will do it several towns at a time.
- You can take as long as you like - the county towns will always be there (although they might change, I suppose) so you younger dudes may be able to complete more of the network that the more senior of us (although being retired might be an advantage)
- You shouldn't really count a town as visited if you got off the train there, in the same way that you wouldn't count having a paddle in the sea at Calais as having swum the channel
- If starting from a particular railway station is convenient, then why not plan your route to visit several other towns, then end up back at the starting point. This would allow you to take advantage of a return ticket.
- No ride logging is required (it's not a race, remember) but it might be fun for you to set up a Flickr page (other photo hosting websites are available) to record the 'evidence' of your bike outside various railways stations and council offices, and some Strava/Garmin connect tracks to help others to plan their routes
- There are no official routes, so you can go by roads, cycle paths or bridleways, as is appropriate for your bike/mood/ability at the time - just stick to legal rights of ways, Ok?