I have wondered about this...If you don't talk to the Jarl of Whiterun and don't give the mage the Dragonstone, the MQ doesn't start, right? So that means no dragons, right? But do you still absorb the words from the walls? I'm wondering if I can collect the words and then start the MQ later in the game, start getting dragon souls, and unlock the words at that point. Does it work that way?
I've talked to the Jarl and given the stone, and still have yet to have a single dragon ahow up. I stated this many times on the forums... as long as you do not go to the watchtower (don't get close enough to it so that the map marker shows up) and fight that first dragon, you will
never see a (live) dragon in your game. I've tried and tested this method on three characters in a row, and have yet to have a dragon show up in game until I choose to actually fight that first dragon. This does, unfortunately have the effect of having an unfinished quest hanging in your journal, and you won't be getting Lydia as your Houseguest until you complete the quest...but having Lydia nowhere near you is a plus in my book...unless she's with you at Boethia's Shrine

As for the word walls, I've been able to learn the words, but until I actually start seeing (and killing) dragons in game, I will never be able to use shouts