Yes, anyone can buy tickets for Mickeys Not So Scary Halloween Party evenings. You can buy tickets more cheaply on the French websites.
In the same way, anyone can buy tickets for Disney Halloween Night, with the more scary atmosphere and parade at midnight.
They only sell a limited number, so when they are all sold, you cannot enter the park at this time, even if you are staying in a Disney hotel,as it is outside normal park hours.
What really surprises me is that they do not sell separate tickets for New Year's Eve, after usual hours, with the fabulous fireworks at midnight, and both parks open until 1am - I'm glad that they don't, but they could easily make more money doing that.
It is not so easy with mixed ages of children, as older ones are going to want different rides and attractions to young ones. Our sons have a 4 1/2 year age difference, so we used to go on some things together, then split up for a while, with DH and I each taking one son, so they could each choose what they wanted to do.
There are currently 16 rides/ attractions in the Studios park - 5 have minimum height rrquirements. Some are not recommended for babies under 1 year.
There are currently 35 rides/ attractions in the Disneyland Park - 5 have a minimum height requirement. The Pirates Beach and Pocahontas Playgrounds have a maximum age and height.
Depending on when you go, some attractions may be closed for maintenance or refurb.
Building is now in progress for the new Ratatuoille ride in the Studios, due to open in 2012.