C'est moi (that's me!!)
I just got back from there. The pin trading was OK. I didn't find too many remarkable things on the CMs lanyards, but maybe things will be more interesting now that the Studios are open, or when there are more visitors.
As for how long you should stay ... I think 2 days should cover it. I was in and out of each park by 3 PM. Granted, I didn't go on every attraction (my back is bothering me, so roller coasters were out), and it was "low" season, but I can't imagine needing more than a day for each park.
Disneyland is a little smaller than the Magic Kingdom in Florida, and definitely has less attractions. The Studios are much smaller than MGM. I don't have the pamphlet with me, but I think there are maybe 8 attractions, some of which have Fastpasses.
I stayed in a hotel in Paris and took the train (RER) each day. It took a little under an hour, but it wasn't too bad.
Have a good time! But, remember, it's nothing like Florida!!