NYE is extremely busy at all the parks. As stated above you will not be able to use her hopper pass at PI as this is a special event. I think last year it was around $75 per adult and included champagne and a dessert buffet, plus entrance into all the clubs and performances by the B52s.
Regular admission into the 4 theme parks will allow you to see their celebrations at no extra charge. Mk is generally a few extra shows, EC has several bands that play in different sections, Studios usually has a headliner band. The year we went they had Huey Lewis & Kevin Bacon. At all the parks they will pass out complimentary horns and hats. Champange is available to toast in the new year.
EC was our favorite we got their around 10am meandered the park not worrying about lines, had dinner and watched each country's cms countdown to the new year with their homeland. So there were NYs celebrations all night. It was so fun. The bad thing was it was in the low 30s and we were very cold. Children were sleeping in every nook and cranny of the park as their parents tried to keep awake to see midnight.
I am sorry to say that you are at a disadvantage staying off property for this holiday. If you want to go to a theme park you are going to have to be there early as once the parking lots fill no further offsite guest are allowed in. For MK be there no later then 9am and for the others 10am. You will have to stay for the day and if you leave will probably not be able to return. Call ahead and make a Ps at the park of your choice and set your mind to wait it out.