Hi, Jaycee! Oh how I love weddings and engagements! If anyone knows how to help you plan your picture perfect engagement, it's Walt Disney World!
You will find some basic information on making your proposal magical
HERE, which is the site for Disney's Fairy tale Engagements. You'll find options here from simple and romantic all the way through to an over the top engagement extravaganza! If you want something super simple to arrange, just ask the nearest Photo Pass photographer to capture the magical moment for you. The best part of that way is that it's completely free, except for any photos you choose to buy capturing the momentous occasion.
As to whether or not Walt Disney World is open to "gay", I have to assume you are referring to the cast members. Oh honey! There's enough pixie dust at Walt Disney World to sprinkle a bit on everyone! You should not find any discrimination from a Walt Disney World cast member, and I am confident that everyone you work with to help make your marriage proposal a special one will help provide the magic you are hoping for.
If you are referring to Walt Disney World guests - well, you will find at Walt Disney World what you will find in the "real" world. Let's just hope that the guests around you when you make that lucky girl an offer she can't refuse have been filled with enough magic and wonder that they can't remember to be negative!
Congratulations and good luck, Jaycee! I wish you both a long and happy life together!