For the 6:15 ADR a Brown Derby, you shouldn’t have any problem to get to Illuminations at 9 PM. It’s about a 20 minute walk at a leisurely pace from the Studios to the International Gateway at Epcot. You probably even have time to take the boat if you don’t feel like walking. Once you get into Epcot, take a look at the flag on the American Adventure – watch the way the wind is blowing it, because that’s how you know where the smoke is going to go. (Hint: You don’t want to be where the smoke is going!) My favorite spot is the area near Germany. It usually isn’t horribly crowded and gives you a good view.
For HS to Citricos, I’m guessing you’re just taking a bus to the GF? You should have plenty of time for that, yes. I haven’t been to Citricos, but just keep in mind the dress code for what you’re planning to wear at the Studios that day:
At this Signature Dining experience, Guests are asked to adhere to the dress code.
Men may wear khakis, slacks, jeans or dress shorts and collared shirts. Sport coats are optional.
Women may wear Capri pants, skirts, dresses, jeans or dress shorts.
Not permitted are tank tops, swimsuits, swimsuit cover-ups, hats for gentlemen, cut-offs, torn clothing and t-shirts with offensive language and/or graphics.