1. You can download Dungeon World Hack while you wait right? The monsters in the back will give you some ideas, but yeah if its only the mechanics you are thinking about its Hp, Damage and Armour.
Remember though that its a narrative game (rather than a combat emulator), so antagonists are much more 'adaptable' to the players levels when they have descriptive and prescriptive 'tags' or moves or narrative cues.
Everything is deeply rooted in the fiction. Thus when the rules suggest you (or one of the players) may have narrated into your dungeon world that your dragons are only vulnerable to weapons forged from dwarvish mithril.... well then you aren't hacking and slashing against a dragon unless you have one of those weapons handy! The GM just gets to make as hard a move as they like. Which may be 'scorch with dragon's fire' or 'lust after a treasure' or ravage the countryside'.
Dragons cease to become simply a number of HP, Armour and a few cool moves (though that's exactly how they are written up) they become an active, evolving creature in your Dungeon World.
2. Sure! Dungeon World gets better and better the longer you play. Remember, the characters only have a back story as long as the list on thier bonds. Everything else comes out through play. The more you play, the deeper the characters and their relationship to each other and the world around them grows. Its your story, make maps like crazy, explore forgotten ruins, save cities, wage war, investigate untold magical mysteries, slay monsters, rule the mercantile world. Its all possible with DW.
The rules at present go up to LvL 10, and they gain some pretty cool moves as they get more experienced. You can adjust the rate of advancement via how many xp you need to go up. There is a 0-level supplement in the works too. I'm pretty sure in the pipeline are advanced moves (12+) for these characters, holdings, retainers, spells, rituals and all manner of earth shaking narrative prompts!