There is no thing like a melee or ranged skill shot. An skill shot is, when you shoot a skill - this can be Maokai's Q, Yasuo's Q, Ezreal's Q or Lux's Q. However, there is a definition between Ezreal#s Q and Yasuo's Q. It's called "short", "medium" and "long" skillshot (Yasuo's Q might be about 220 range, while Ezreal could be 900. I don't remember the correct ranges). Ezreal's Ultimate for example, is neither short, medium or long, it's global, meaning that it goes the entire map along.
And what means "slightly longer range than a normal dash"? There's many different dashes, there's no normal dash... well, ...
However - I can't read what you want. If you want the ranges of all of your abilities, or just the range of your Champion's basic attack range.
If basic attack range only, then 550 range. It's the safest choice, similar to Vayne's range. With two skillshots, two dashes and a knock-back, then I would consider 550.
You might want to see for yourselfs on the ranges of skills and AA on the wikia. Here's Ezreal's profile for example http://leagueoflegends.wikia.com/wiki/Ezreal