World-of-warcraft – How long does it take for the legendary naval mission to respawn

If we were to compare it to WotLK and you're inquiring about obvious effects of the surge, like queues, etc, I'd say a week to a month depending on the size of your realm. The more players on the realm, the longer the surge will last. However if you're referring to the crowding in the starter zones, e.g. Vashj'r or Mount Hyjal, that's already starting to dissipate as people spread out over them.

The amount of guild experience awarded varies. It is depended on specific factors... (Source)

Guild xp for boss kills is scaled on a few factors.

• Boss level
• Normal / Heroic
• Amount of guild members present (more xp for raids, since they are limited to once a week)
  • 20/25 - 25 player raid
  • 8/10 - 10 player raid,
  • 3/5 - dungeons
  • 8/25 - Old 25 and 40 man raids (Vanilla, TBC, and WOTLK)

Straight from Blizzard's Mouth (Source)

The amount of experience gained scales, with 3/5 guild members granting 50% normal guild xp, 4/5 giving 100%, and 5/5 giving 125% guild xp. The amount gained from each boss scales with your level relative to the boss's level, with Heroic bosses worth even more (1.5x). It pays off to have a full group of guild members!