2) It is not very sure whether if it can be prevented, however ther are attempts to tame them before they could cause any massive damages.

3 The term typhoons will be given when there is a constant wind speed of 74 miles per hour being reached.

However, the force of typhoons usually wanes through friction with sea or land surfaces, and is also influenced by temperatures and wind force in the surrounding atmosphere.

4) The worst typhoon in recorded history was 1959’s Typhoon No. 15, later named the “Ise-wan” (Ise Bay) Typhoon by the Meteorological Agency. The colossal storm, which at times generated wind speeds of more than 180 kph, made landfall in Wakayama Prefecture on Sept. 26. It took 5,098 lives and left nearly 39,000 people injured, while 40,000 houses and buildings were completely destroyed. It was the largest number of deaths caused by a natural disaster in Japan until the 1995 Great Hanshin Earthquake killed 6,434 people.

I hope that helps ^^

go to http://www.senri-i.or.jp/amcon/typhoon.html