I've not read other's comments so sorry if they have already stated some of this. I'm just going to answer the questions to the best of my knowledge.
Yes the roads can get congested but with going on a Thursday either way will be about the same. Although If you have not been in a while the Veterans Boulevard entrance (the one by Dollywood's Splash Country) had two booths now and can accommodate up to four cars at a time and has a possible usage of two lanes going in. Either way coming in it doesn't really matter what will really save you time is when you exit, exit through the Dollywood's Splash Country entrance because they have a red light at it and have two lanes exiting at a time. While the Dollywood Lane entrance only has one lane exiting at a time and has no red light.
Nope there won't be any festivals going on Festival of Nations ended May 7th and KidsFest doesn't start until June 15th. No the crowds shouldn't be to bad (don't kill me if they are please.) I would say if you get into the parking lot at 9:30 to 9:45 and you are parking half way between C and D I would go ahead and get a Q-bot because it will probably be worth it (maximum of six people on a single bot but if the three year old sits on someone's lap no extra charge.)
No snacks are not allowed into the park due to health reasons but since the girl does have a allergy they will allow it. And usually for kids they allow really any kind of snack because most will not eat "big people" food.
I would head up to Craftsmen's Valley first after Timber Canyon and hit Tennessee Tornado, Blazing Fury, Daredevil Falls, and Mountain Slidwinder.
The wettest seats on Daredevil Falls are usually the front other than that you don't get much. Mountain Slidewinder if you know how to you can get extremely wet (and I mean my group has weighed several pounds more after getting off and going to re-ride it) or if not you can get mildly wet. Blazing Fury not much at all it is more a indoor coaster featuring water not a water ride featuring a coaster. And your right about the River Rampage no one can tell you if your going to get wet or not because the person next to you may get soaked and you may not get hardly a drop.
If you like 50's and 60's music Dreamland Drive-In is a must!!! I loved this show I at least saw it seven or eight times last year.
It has also won the IAAPA 2006 Heartbeat award and an honorable mention in the show with a budget of $500,001 - $1,000,000 category.
Well trust me unless you are completely blind no matter where you go in Dollywood you will see these skillet's. They cook footlong hot dogs in them in Timber Canyon. They have sausage works in the Market Square area by the fountain, along with cheese steaks being made in skittles in Market Square. Up in the Village they have flatbreads in them. So really they are every where.
The best "skillet food" I think Dollywood has is at PaPaw's Flatbread in the Village area. It is your choice of either chicken or steak with pepper's, onions, cheese, tomatoes, lettece, sour cream (you choose from the toppings they put on.) It is delicious. Plus near there is Victoria's Pizza and the three year old would like it and you could all go eat in there and sit down while you get the three year old's food. If you eat here for lunch I would go to the Country Fair area afterwards for the rides in that area.
Another place I like to eat is Red's Diner in the Jukebox Junction area. It has good hamburger and GREAT shakes.
Hope that helps if you need any more help just post and I will be happy to reply.