You are on the right track, AZBooks.
I would recommend that you do as you already has, add the books one per directory and update metadata and cover.
Most of these steps are described in the fine manual:
http://manual.calibre-ebook.com/gui.html#actions
No need to do a conversion to the same format(s) after. When you save books to disk, they are automatically updated with new metadata and cover.
Instead edit the save template and decide how you want the folders for your books to be organized. Perhaps genre/author/title.filextension?
Then save the books to disk, using this save template. After that copy the directory tree to your NAS and your laptop and start reading.
After that you can delete the books in calibre, or keep them there as a backup. Nice if you decide you want another directory structure or get some ebook reader. Or simply add more books.
By the way, nice to see younger people taking an interest in calibre.
