They give around 500-550 gold that I've seen so far and there's normally one up in each zone do it on your main and alts and it's a quick little way to get a gold bump
The bug squishing world quests are available earlier than that. I did one a few days ago and I'm currently only renown 5, maybe lower when I did it.
They can rarely drop drake customizations but it's not very common. After doing all 4 dailies on 4 characters for two weeks, I got one customization. In general, just expect gold and supplies.
The bug squashing one is kinda annoying but the every WQ reset the dragon races give 500ish gold per so it's decent gold for very little effort.
Hmm, I did a supply collecting one near Uktuluk Pier last reset and I was at Renown 3 with Valdrakken Accord, so they either unlock earlier than 7 or its availability was a bug.
Completing the achievement "Just Don't Ask Me to Spell It" starts the world quests. And the achievement is account bound so do it on one toon and the WQs are open to all. It also puts up the icons to show where Elemental Storms are. BTW, the toon I completed the achievement on had a renown of 6.