In Gmail, I can attach a file from my google drive.
On the reverse direction, in google drive, can I access the attached files of received emails in gmail? This is useful when I lose access to my gmail account.
Gmail – Possible to access email attachment from google drive
gmailgoogle-drive
Related Solutions
Sign out of Google Drive from the incorrect Google Account.
Attach a file from Google Drive and login to your Google Account to re-authorize Trello's access to your Google Drive.
Does Google Drive sync with Local Folders? e.g. I have a folder called work (c:/work). I drag that folder to Google Drive Desktop, it syncs. Thereafter I create a new file in (c:/work). Will Google Drive sync that new file, or must I drag it into Google Drive Folder manually.
Not in that way. The desktop portion of Google Drive works essentially the same way as Dropbox: There is a special folder (usually called "Google Drive") in your file system. Whatever you add to that is synced with Google Drive. Whatever you remove from there is removed from Google Drive and no longer synced.
If somehow I lose all my files on Google Drive Web. When I login to the Desktop Application, will it sync and remove all my files, or will it sync the files in the Desktop App back into the web account.
How would you "lose all your files"?
If you remove the files yourself via the web interface, then, yes, they'll be removed from your desktop file system (assuming your PC is running and the app can connect to the Internet). However, they should be in your "Trash" folder so you can recover them.
How else would you lose them via the web? If you lose access to your account then the desktop sync app won't be able to log in and sync your files, so they shouldn't be touched.
There's not really a "login" to the desktop app after you've set it up. It runs in the background and you don't really interact with it directly. (Again, very similar to how Dropbox works.)
Are there any other limitations as well as more efficient methods of using Google Drive for my work?
That's rather subjective and not really answerable. We don't know how you work.
You should have a look at Google Drive in the Help Center.
Best Answer
Short answer
Yes it's possible, but it's required to extend Google Drive to be able to do so.
Explanaition
Users could authorize apps created by themselves and third party apps to access their Gmail mailbox, like a desktop/mobile email client among others, so it's possible that if the user "lose access to his gmail account" on the web, he still be able to access the messages and the attached files to them.
Google Drive is not a third party app, so if the user "lose access to his gmail account" he could not access Google Drive with that account. Besides this, Google Drive doesn't has a built-in feature to access Gmail messages attachments but it could be extended through add-ons and Google Apps Scripts.
References
Apps connected to your account - Accounts Help
Extend Google Docs, Sheets, and Forms with Apps Script - Docs editors Help