1. Find Ami's best friend Nero in Merged World on an island with ice; it's the only solitary one with a house. Use Ami as the lead to trigger the key event.
2. You will get the best relic once you find ALL 20 Memoir Pages (12 from Gaia, 8 from Merged world), then talk to Mid in Branch to trigger the event.
3. Kokkol (see Memoir Pages), regarding Odell Station man: find Vommamoths and get the fang drop, fight drill looking machines in Kasion Tower to get the ore drop and lastly you will get the Pure Nethicite in story mode treasure chest where Topaz Weapon awaits.
4. Babil Tower is story-related; complete the story more and it becomes open.
5. Revisit ALL the towns/villages with the CLAW insignia for marks. The fights are manageable if you're powered up.
6. I have no answer because I don't use Bosch. He's just comic relief filler to me.
7. You can sell them for 500gil each.