I keep a list of my favorite places at
Disneyland to eat gluten free on my blog:
http://glutenfreetop10.blogspot.com/p/disney.html
I was just about to write up a blog post that summarizes what I had where - once I do I will put a link on the text "Disneyland Resort" at the top of the list.
There's plenty of great safe food - having to go gluten free is quite a change to everything you thought was normal for about 6 months, then it gets easier. Disneyland makes it sooooo easy. It's the best place to travel if you can't eat gluten. I'm sure you've already figured this out by reading the super thread but Disney does it all the right way when it comes to making sure folks with food allergies/intolerances can eat safely. It's all part of the Magic.
As for treats, the main stuff that I know is safe is the dole whip and ice cream sundaes which you have the manager make for you (I've had them at Ghirardelli in DCA and both of the main ice cream parlors in DL and DCA). I had a decent pre-packaged gluten free brownie at Jolly Holiday Bakery and on my b-day at Blue Bayou last year the chef made me some sort of chocolate mousse Mickey but I've never seen it again so I may have just gotten lucky that day. On our most recent visit in May we had a very tasty Panna Cotta at Carthay Circle.
If you are going during any sort of celebration (of just want to do something extra special) you can pre-order a gluten free cake to be delivered to an on site restaurant or hotel room. I had a decent (OK tasting but absolutely gorgeous) gluten free birthday cake last year. You need to pre-order a few days in advance, I'd do it a week in advance to be safe. I tear up every time I think about how special it was to actually be able to eat a professionally baked and decorated cake I could actually eat.
Most of the handmade chocolates made at the shop on main street are AFAIK not made of gluten ingredients but could be a high risk for cross contamination since other handmade treats do have stuff like pretzels in them. I've had the English toffee and chocolate/caramel/pecan turtles w/ no side effects (I am very sensitive) but eating is risky it's a personal choice what you try. If you ask any cast member in that candy shop they will tell you everything has gluten in it due to cross contamination concerns. I always bring gluten ease 2x tablets with me just in case I think I've been glutened but so far I've never had to use them at a Disney resort. They can usually cut down the severity of my reaction if I take them soon enough.
good luck and have a great time!