@Misapoes
For colors/icons see my very recent post here:
http://qbforums.shiki.hu/index.php/topic,703.210.html
And about the stop/pause feature: In the coming v3.2.0 there is one more feature that might put users at ease. Now if qbt doesn't find the files, it displays a status message of "Missing files" and autopauses the torrent. If the files reappear(after the user has closed the app) qbt will behave as if nothing had happened previously.
I know that this doesn't end the pause/stop debate.
However you said that you needed a fast way to see what is completed and not "just paused". You can achieve that via the "Completed" filter in the left panel.
The color scheme is reworked and paused torrent will not use a red color (see above post).
I hope I didn't sound aggressive.
PS: qbt doesn't waste resources when checking for files existance. It only does this check during startup where it tries to verify that the fastresume data are still valid.
After all the above can you tell me, what is your current view about pause/stop?