Calibre - new starter with a collection

Hi guys,

First of all, i'm a new starter to Calibre and find here a beautiful tool. We can tell it's been well developed.
So I was looking for a tool management for my collection of comics... and Calibre seems to fully respond to this. As my collection is around 10go of data of comics, you can understand the need of it. There are so far stored on a NAS server and i'm still doing test with Calibre .

So far, I got the feeling I'm oblige to duplicate all the files to be store in an empty folder, which be used to create the database... all done automatically when I'm create an entry.
Is it something I'm oblige to or can Calibre used path to link the file to the Json database? It's something will be fairly impossible or will take severe days to do. (I'm running a folder right now of 28 files, and it takes at least 30min).... probably cause it's stored on my NAS server and not on my hard drive.

When I update the metadata, Calibre seems to change the directory structure.. as part of its way of reading data ?
Any info regarding this will be great.

Thx you again for this software and looking forward to use it correctly.
yOta