How is this better than the in-game quest helper thingie? While that shows you the destination of your quests it doesn’t show you the best order in which to take them, which to skip, and when to move on (such as when you’ve out leveled the area.) .  Zygor’s show you the optimum path to take to complete the most quests in the least time, which will save you lots of time over the quest helper.
Island Expeditions are three-man scenarios that pit the team against three enemies using what Blizzard calls “advanced A.I.” That means the enemies will act more like players, pursuing goals proactively and filling class roles. The expeditions take inspiration from action RPGs, with randomized areas that mix up the experience each time. Players’ main goal will be obtaining resources more quickly than their foes, and expeditions should last 15 to 20 minutes. While primarily meant for PvE, there is a PvP mode that replaces the opposing A.I. with teams from the enemy faction.

Make sure you have the two Flight-Path toys purchased, as this can save you time. It won't have EVERY flight path, but will have major locations for faster travel if you need to switch zones entirely(which you will). If you buy the toys on one faction, it unlocks for the other faction as well. So don't spend double the gold! These toys can be found at the heirloom vendor(Undercity for Horde, Ironforge for Alliance)
I've hit level 65 recently and have noticed my leveling speed drop really fast, I knew this would happen but I'm just looking for ways to become a little more efficient with questing. Right now I'm zipping all over the place without much idea on what to do first. Would this ruin the gaming experience though? (I'm still planning on reading all the quests for story). Or is there any alternatives with a lower price tag?. Also is Zygor guides actually any good? And lastly, (sorry for all the questions) is using it going against WoW rules?
DoTs: Assuming that the mob is going to live for certain periods of time, it is worth it to place DoTs up. If the mob lives for at least five seconds, cast Pain. If it lives at least seven seconds, cast VT. The ideal time to cast DoTs is when it would be replacing Flay, but you can substitute Blast if the mob will live longer. Make sure to cast Bolt on cd though!