Most of the terms, as well as diverse techniques are explained in this tread:
http://forums.deeperblue.net/beginne...reediving.html.
Packing is not without risks, but extrem situations may require extrem approaches. Besides Eric's website, you can read more about packing and its risks for example here:
http://forums.deeperblue.net/safety/...rtrapping.html
ImpulseAdventure - Freediving - Lung Squeeze
freediving - squeeze
http://forums.deeperblue.net/special...e-squeeze.html
http://forums.deeperblue.net/freediv...tml#post618592
http://forums.deeperblue.net/spearo-...g-packing.html
http://forums.deeperblue.net/general...arotrauma.html
Another good solution would be getting so fat that you won't sink anymore
Or eating a lot of beans
As for hyperventilation - that was discussed recently in several threads. Generally it is not advised, because it increases the risk of blackout, and because it suppresses the diving reflex, but again, assuming you will be in an extreme situation without having sufficient time for training, it may help you. Read more for example here:
http://forums.deeperblue.net/static-...questions.html
http://forums.deeperblue.net/beginne...reathe-up.html
http://forums.deeperblue.net/safety/70077-sambaaaa.html
http://forums.deeperblue.net/static-...perventilation