I think for central Paris door-to-door nothing would compete in time with the Eurostar (it's top speed is significantly faster than almost all light aircraft)!
I plan for 155 knots and given the channel is in the way and its much further to get to Ashford or London in the first place I will beat the Eurostar every day of the week.
I will even comfortably beat it with a stop at L2K, Lognes, taxi and train but direct Lille and the Eurostar I suspect has the edge on going to Lognes.
Then again if we flew to save time, we probably wouldn't. I always reckon that by the time you get to the airport, sort yourself out, and get from the airport to where you are going at the other end its got to be at least a two and a half hour car journey to save any time or someone has to put some water in the way. On the other hand I did Bembridge the other day in 15 minutes, try that by car and ferry!
Toussus and Melun are both find and have been to both in the last few years anyway. No problems and as exactly as the AIP. I have never been to Bretigny.
Contacttower - if you give Lille a go, you will be directed to the huge GA apron. You pay in the deserted terminal in front of the apron. If you belong to a flying school the fee is discounted and its about 12E. You can leave the airport via the main terminal but if you dont want to wait for the bus to take you over there is a gate just past the GA terminal. You still have to walk to the terminal for the buses or taxis but the taxi driver can drop you back to the gate. Customs can be a pain. If an international flight has just arrived you are straight through - if not in the usual way maybe they have to drag them away from the coffee shop and it can take half an hour. The buses as I mentioned are every half an hour from the front of the terminal and go the station, there is usually a fleet of taxis all looking for a fare. Lille ATC are excellent and will give you a service from the French coast if you wish. It is of course a straight line from the coast to Lille with nothing to bother you except perhaps the nuclear facility at Calais if you happen to be that far East and low level.