Map Pieces

One of the most look forward features of the Cruz de Sur was the discovery of sunken ships. However I now have lots of questions regarding this.

First and foremost, I hope there won't be any more person claiming to know how much map pieces I have collected. One is enough already. T_T I'll list down my questions and the answers that I've found. If you have anything to share, please leave a comment.

1. The sources of map pieces?
A: So far I know you can get map pieces through trading, fishing, fnding (視認), collecting (採集), battling, treasure box in sunken ships, ship building, reporting Adventure quests, searching anywhere outside towns. Anywhere else?
(Thanks to cain, weiting, 小愛.)

2. Is it limited to specific geographical areas only?
A: No. You can get them in Europe too. (Thanks to 上杉.)

3. For trading, does it matter whether you deal with the Marketplace Owner or the Marketplace Apprentice?
A:

4. For trading, does it matter whether you sell or buy?
A: So far, it is confirmed that buying goods will get you one. (Thanks to sushi.)

5. Will trading with other NPCs give map pieces too, i.e. 行商人, 工坊工匠, 道具店老闆, etc?
A:

6. For battling, does the relationship between your opponents and your levels affect the probability?
A:

7. Is there any daily limit per person?
A:

8. What is the most successful method for getting the map pieces?
A: Battling.

9. Will learning Salvaging and Towing increase the probability?
A:

10. Is getting map pieces from reporting back to the quest giver the same as reporting back to bar girl/boy?
A:

In the end, I can just say that, Koei, please increase the probability of getting map pieces!