Hi Luisa! If you make dining reservations at any of the resorts, the only pass you will need is a parking pass if you happen to be driving to the resort. To get this pass, simply tell the security guard at the resort that you have a dining reservation and they will either wave you through to park or give you a parking pass for a specific amount of time. If you are not driving, you do not need a pass to go to another resort.
There are some restaurants that are located inside a park. In this case, you will need park admission to get to the restaurant.
As you research Disney restaurants, I'd like to suggest you visit the
restaurants page on disneyworld.com. Disney has been working hard to update this page and you'll notice you'll be able to narrow down your search by using the filters on the left side of the page. For example, if you want to find all the dining locations in Magic Kingdom, click on the "Magic Kingdom Theme Park" check box and you'll see only those restaurants located in/near Magic Kingdom.
You'll also notice you can now book your reservations online as long as you are within your 90 day window. I recently used the new process and it seems fairly easy. You also still have the option to call Disney at 407-WDW-DINE to make your reservations.
I hope this helps - please let us know if you have further questions. Diane :)