Bike
4.1 Do I need a special kind of bike for triathlon?
No. If you're just looking to enter a triathlon to finish and enjoy the personal accomplishment then just about any bike will do. To be more efficient and competitive you'll want to have a good bike designed for racing. There is some disagreement within the triathlon community about whether road bikes (sometimes referred to, inaccurately, as "10-speeds") or hybrid bikes (which look more like mountain bikes do) are better for triathlon. I happen to prefer a road bike but ultimately it comes down to what you're most comfortable and fastest on.
4.2 Is drafting allowed?
Read the race rules for your race but usually no, it's not. At least not on the bike.
http://www.factplace.com/triathlon.htm