A couple of quick questions

[abaraikenshi]

With Zygor's Guide, does it know which quest we have and haven't done yet? Lets say I leveled up to 75 on my own, then bought Zygor's guide and selected the appropriate one, would it "know" which quests I have done?

Is there a profile for 68+ that starts in Northrend?

[cabby]

Yes, the guides will query the WoW server to find out which quests you've already completed so that it won't try to have you do them again.

For getting into sync with a character 70+ do the following:

Go into the Dynamic Progression section of the guide options, un-check the 4 boxes, and adjust the slider up to 80.
Select the 70-72 section of the guides and right click on the next step button. The guide might stop on travel steps (i.e. get a FP or go to such and such zone) and if it does right click the next step button again until you get to a step that wants you to accept a quest.
Follow along with the guide from this point. It might have you doing some quests lower level than you but there are so many quests that are dependent on other quests it's safest to just do them.