score:6
There still is no independent travel to Tibet. You need to prearrange your trip through a tour operator and a guide is required. If you plan to travel outside Lhasa, then a driver is also required.
But it is not NK style, you can wander around in the cities on your own, no need to have your guide at your elbow all the time. But since you have paid for the guide, it never hurts to utilize their knowledge about the sites, market bargaining, ordering foods, etc.
The Tibet Travel Permit is a separate set of papers, not something that gets stamped into your passport. The tour operator will arrange this for you, they will need your passport details but not the actual passport. You will need this permit before you board your flight / train to Lhasa, so need to plan ahead far enough to allow processing (2 to 3 weeks) and mailing the hardcopy to you. If your guide is meeting you before the flight / train to Lhasa, they can bring it with them.
There are areas outside of Lhasa that do require additional permits, your tour operator can fill you in on what might be needed based on where you want to go.
The train is basic Chinese carriages, neither high speed nor first class. Compartments with doors have 4 berths, non-closable compartments have 6 berths. You can book all four berths and have a compartment to yourself if space is available. Train travel time is around 40 hours from Beijing.