Here's some extrapolation based on what we know about Quinn's mechanics, along with some fun (non-washed out) plays I caught in spectator mode today. Along with the previous video I think this pretty well covers the current state of Quinn & Valor and I hope it's giving you guys a lot to look forward to (as well as an edge when she's actually released).
I know I said this a lot in the last video, but don't stress over the ability differences between ranged and melee form. The only thing that's changing is your abilities are designed for melee range when playing Valor, they're still effectively the same things. It's not Jayce, Nidalee, or Elise. It's not even Shyvana. It's just a simple and fairly unique interaction.
There will inevitably be someone crying out, "How can you release a guide for a champion that's only 2 days old?" And I totally understand you. But this is how she plays, and it's pretty straightforward, and somewhere down the road I'll have a release guide for her, too. :)
Couple new mechanics that weren't mentioned in the previous video:
1. Enemies can normal attack you after you dash towards them with Vault, before the jumpback.
2. You regain your movement speed after being in combat as Valor (this is kind of a no-brainer but I realized I never actually tested it).