Jeremy,
I'm sure that many others will also reply. There is also much on this site that will give you the answers you seek but to save you hunting:
1. Toilet facilities seem to have improved over the years. Loos in ACO stand still the best on site. Pikeys on the doors the same wherever you go though.
2. ACO tickets for the more popular campsites basically gone before the conclusion of the previous year's race. Beausejour is the only site I am aware of that is still available from the ACO as of now. Same with the ACO grandstand (unless you go via a ticketing agency and pay through the nose). Other grandstand seats were still available from the ACO as of 2 weeks ago.
Yes you can still park at Mulsanne/Arnage with your general tickets. Whether you will want to brave the horrendous traffic though is a different matter.
Other changes: You will see a lot less trees around the Esses area, along with a new grandstand. The run down to the esses has been remodelled - some approve, some don't. Oh, and the funfair is now at the top of the village, and all of the more 'interesting' attractions now gone.
I'm sure there are other changes I've forgotten so will leave it to others to fill you in.
