I thought there was supposed to be a cease fire between the Stormcloaks and the Empire until the Dragon thing was settled.

Right now I'm going through the Legion questline and now I'm about to deliver an axe to Ulfric. It doesn't seem like a peace deal is going to come out of this. Did I mess up somewhere along the way?

Should I be advancing the MQ instead?

Well your doing the legion questline and not the main one so of course your still fighting.

Stop the legion questline until you finish the main one, however as far as im aware it has no real effect on the way things play out unless you lose Whiterun then im not sure about catching the dragon. I did the main questline before doing anything else.

So, just to be clear, the part where the Stormcloaks and Empire meet at High Hrothgar is a part of the MQ? Finishing the MQ will establish the peace agreement which will last until I "choose sides?"

Season Unending is bugged. In my case Tullius and Ulfric don't have the relevant dialogue options.

There is no real peace between them so no matter what you do they still hate each other I was doing the legion quests yesterday and it was long after I did the MQ and ulfric was still talking about waiting until I delt with the dragon problem.

Just capture the dragon before you start fighting ulfric just to make sure. The legion/Stormcloak story only advances when you do the missions for one of them.

OK, what I'm still not clear on is which questline has the part where everyone meets at High Hrothgar? MQ or the Imperial/Stormcloak?

Main Quest.

Thanks...

For obvious reasons, this part doesn't happen if you advance far enough in the Imperial/Stormcloak questlines.

I'd imagine if you advance far enough you can just use whiterun, the jarl is who sends you on the peace treaty quest.

Same here, no relevant dialogue option for Ulfrig. So as a revenge i joined the Legion