shorting

I'd like to open a discussion about Shorting, mostly so that I can learn more about it. Over the years it has been cited as a blight on various markets, to the point that it has been suspended, but then reinstated, in times of dire need, ie the GFC. I can't see that it is ever in the interest of the REAL mkt and it should be, along with HFT, banned altogether.
Example: I am a holder of FDC. The FDC share price over the last few months has barely moved, despite a string of solid announcements. Holders could stoically think that such is the mkt, but NAB let the cat out of the bag a month or so ago when they allowed their interest to creep above 5%, and so had to declare their change of interest regularly for a period. Suddenly it was clear that NAB are probably regularly shorting their FDC interest, and it is a part of their investment stream. Far from being a loyal and supportive shareholder, NAB are in the stock because it is solid, unlikely to fall over, and they can manipulate it to achieve a regular investment outcome. Are all of our banks doing this to Australia's solid but second tier companies? Can someone refer me to good sources on shorting practices in Australia?