Blizzard Characters We Want in Heroes of the Storm
Heroes of the Storm draws its roster from multiple universes, but not everyone has joined the battle. Zorine Te names some favourites she’d like to see.
I thought it'd be really cool if they did a contest for their WoW players and the winner would have their main character added to the Heroes roster. Other than that, I don't know who's already been confirmed so I can't say for sure who I'd like to see included lol.
Gameplay wise, it's very different. Blizzard have changed a number of mechanics and introduced things like team leveling (the team is assigned a level, as opposed to individual player) and objectives on maps etc.
If you are interested you can get more info from Martin's excellent preview: http://www.gamespot.com/articles/how-heroes-of-the-storm-is-different-from-and-the-same-as-league-of-legends-and-dota-2/1100-6418405/