I don't work for them, but I feel like I've heard these questions answered enough to give you an idea if the AMA doesn't happen.
How do you come up with genius scripts like Inside Out?
I've always heard their directors say that their stories usually start off as nothing. Kind of typical and bland. They are constantly revising their stories until it feels right, and can sometimes last into the production phase. They have an inner-group called 'the braintrust' which is a collection of their directors and some others which will sit down in meetings in which the director will explain where their story is and the group will be blunt and honest with their answers. The director has the freedom to choose which advice they would like to take. I've heard that Brad Bird is notorious for always having something great to say.
What is it like watching the completed film for the first time after production?
Most people working on the film see bits and pieces of it being put together while production is happening, but don't get to see it all put together until the end of production. I'm sure it feels rewarding.
How long does it take for a Pixar film to be produced?
It seems like an average would be 4 years, give or take. Some films are revised and changed quite a bit and can take much longer. A recent example would be TGD.
What is the best part about working for Disney Pixar?
I've heard that it's working around such great artists.
What goes into production of a Pixar movie?
Starts with an idea. Then a pitch with some basic story arcs and concept art. When it gets approved it would probably head to story writing, script writing, concept art, and story boarding. After the rigs and sets are built, animation would start. After a shot is finalized, it still has to go through lighting and other rendering stages. Somewhere in all of that is the music recording, voice recording, and matching that to the animation. Never quite figured that out, besides voice acting either comes before animating or runs simultaneous, considering they sometimes use mannerisms from the voice actors in their character's animation.
I'll probably delete this later (or it might be deleted for me), so copy and pasta if you'd like. Hope these answers helped satisfy your curiosity a little bit!