Wayfarer

I'm trying to do this special event missions, because the wiki says you can ultimately get a tormented weapon, but I'd like to know how much the event will last!

Do you mean till when you have the time to finish the quest?
A: Till the 30th of august

Or do you mean how much work it is to get all 4 quests done?
A: My toon didn't use a running build nor any speedboosts and has all outposts in the game unlocked. It took me bout 3,5-4 hours to get it all done

I need to reach the bloodstone for the northern quest: I completed gadds quest in the bloodston cave, but the quest didn't check the bloodstone off... what should I do?

Also, it took me an hour to reach the wizard tower region, and I couldn't get to it because I died to often... is there a way to increase survivability?

For the shiverpeaks bloodstone you need the quest crystal method given by Saedan in Gadd's encampment. You need to enter and do the dungeon, not the pirmairy quest (instead of talking to the incriptionstone outside the area, walk through the door with the purple sign on it and use the portal, you need the former named quest though to have the right spawns to proceed to lvl 3.

The dungeon is a lot harder then the primairy quest (more foes, and it is stacked with traps).

The trick to getting to the wizards tower is pulling and avoiding overagro. You could also kill the group all the way to the left of the higher part and use the skill necrotic traversal to bypass the biggest groups.

Grab the Crystal Method quest from Saerin in Gadd's Encampment. With that quest active, you'll be able to get recognition for Bloodstone Cavern.

What's your group setup? What hero's and skills? Also, are you leaving from Temple of the Ages? I ask because you can leave with a group of 8, rather than 6 from other outpost's in the area - and the extra firepower can definitely help out.

I recruited some players to help me and started from temple of the ages, and it went way better!

Now I need a couple of tyria locations, some cantha and all the elona mainland locations. I'll finish canthas main questline tomorrow, so I think I wont have problems finding the places there, but what about Elona? I only did the first cooperative mission. Should I complete the main questline there or would a runner be enough? I'm leaving for a week on August 25, so I don't have much time to complete this quest!

Elona is a LOOOONG run which is a lot more difficult if you don't have Junundus unlocked. I rather recommend finishing the questline, because a lot of the locations are out in the middle of nowhere (Hallowed Point, Crystal portal).

I'll try doing the quests then!