FlyerTalk Evangelist, Ambassador, British Airways Executive Club
Join Date: Jun 2008
Location: Somewhere between 0 and 13,000 metres high
Programs: AF/KL Life Plat, BA GGL+GfL, ALL Plat, Hilton Diam, Marriott Gold, blablablah, etc
Posts: 30,546
It would be best if you posted your questions on the thread that you already created, which is the normal practice, rather than start a new thread for related questions on what's not to be missed. Just do a search and you'll find fairly exhaustive answers.
That said, there are many existing threads which also answer your questions on how to maximise the F experience.
On the other questions:
1) there is no way of merging separate PNRs. You can have them cross-referenced but it is of very little impact, for instance it would not protect you if your previous flight is late;
2) your choice of buying a "wasted" CDG-LHR flight just to use the P lounge after you landed in CDG whilst you are in fact flying from ORY strikes me as an extremely poor idea. In most European airports, and certainly for international areas - which is where the P lounge is - departures and arrivals are fully segregated. That means that once you are in the P lounge, you will not be able to just exit as you wish. You will need to go to the lounge people, find some lousy excuse to explain that your plans have changed, and get them to effectively call a police/security escort to let you out of the departure area. Besides, you will not only inconvenience everyone but make a fool of yourself because the typical P lounge crowding at any given point in time is between 1 and 10 people which means and all get a very personal service, which means that the agents will be very "personally" aware of what you have done, which is to use the P lounge under what amounts to a false pretence (something that will be very obvious to them when you ask to exit as they will see that you in fact have a flight from ORY).
So I would say that your first move if you want to have a great F experience is to immediately abandon that silly plan and get that wasted CDG-LHR refunded. AF people are not complete idiots and it would not be fitting to treat them as such.