Now that I've done it myself I thought I would write up a guide to help others complete their own 100% world completion achievement the fastest way possible.
Be like Snake! :P
The Scout:
Fastest paced character from what I can see is the Thief. Remember your mission is to scout, not to fight every critter that happens to be in your way. I won't go into traits as you will be able to work out what you like best with this, but the skills you'll want to be using are:
Steal covers a lot of ground and useful for escaping mobs if you use your targetting correctly.
Hide in Shadows is useful when things get hairy, go invis.
Signet of Shadows but never actually activate it. Passively it will give you +25% speed continously.
Shadow Refuge - Switch out with Signet of Shadows when you are going for a commune or combat skill point. 7 seconds invis is more than enough to commune!
Shadow Trap is useful as distraction while you flee, or as another damage dealer if you choose to fight.
Thieves Guild the same as above but x2.
Roll for Initiative - gets you much needed init and more importantly is another -moving- skill you can use to escape.
Gear to Bring:
Double Daggers works well for mobility, since you can Leaping Death Blossom "through" incoming enemies and cloak and dagger into stealth for an additional escape. Remember, you run faster -out- of combat though and if you are fighting try land your first strike from hidden to your target's back for maximum damage. A shortbow is handy too to help with some heart tasks, like shooting dredge turrets and such but if you prefer something else go for it.
Underwater primarily use a spear. In close quarters and one on one, you should be unstoppable (unless you are poking a megalodon you idjit). Spam your block attack (3) to regain initiative then (5) to spend it all while dodging.
The Zones:
This may seem counter productive but do not scout zones geographically - like, don't start at Rata Sum and work your way across to the Blazeridge steps. The level difference can hinder you quite a bit if you are not in an appropriate zone. It's easy enough to work around though. Your first rule is to never move on until you've completed a zone entirely.
Now to your actual scouting sequence: Start out by completing each city - including Lion's Arch.
Then use this listing here.
Do all the lowest level zones. Then do the next lowest level and so on, leaving the level 80 stuff for last. As you complete each "tier" (like all level 1-10 zones) return to Lion's Arch for some crafting for a small level boost. You'll be able to gauge when to do this anyway since your bank will be filling with mats as you go - this is if you are harvesting majority of nodes on the way (and you should especially if they are unguarded).
Hearts:
Always chat to the heart person first as half the time the fastest way to complete a heart is a non-combat method. A good rule of thumb for "collection" stuff is get 10-15 items first before heading back to hand them in.
Skill Challenges:
Memory Test - easily accessible for anyone anyway
Food - if it is guarded, throw down a shadow refuge AT the food as you are running at it. Take and eat it, stealth out.
Commune - Same as food. If it is very well guarded throw a thieves guild and shadow trap to keep the enemies busy on your approach. Underwater you will need to kill the guards. You can still bring thieves guild if there's a nearby shore.
Fight - Use thieves guild and shadow trap followed by steal if you have "thrill of the crime" as your NPC pals also get the bonus. Follow up with cloak and dagger and backstab. If the enemy survives just kite while throwing daggers (and/or caltrops) and stealthing until your thieves are ready again. In cases with many opponents just aim to kill one at a time then flee/recover. They hang around for awhile anyway so don't rush.
The Mists:
As the old adage goes: If you can't beat them, join them. Make use of the free server transfer and hop onto the dominant of the 3 warring realms. You need to move fast though as the landscape of who holds what is prone to change. Dedicate at least 2 hours to finishing everything here and hop between the three borderlands and the eternal battlegrounds each time you hit a "block", coming back later to see if your side has retaken what you've not yet scouted.
