70.3 = distance of a half-ironman or "long distance" triathlon. 1.2 mile swim, 56 mile bike, 13.1 mile run.

WTC = World Triathlon Corporation. They are the company that owns the rights to the "Ironman" and "Ironman 70.3" names. WTC organizes races and licenses the Ironman and Ironman 70.3 names to various race organizers around the world to run the Ironman and Ironman 70.3 series of races. It also organizes the world championships for those race series (Kona for Ironman, Clearwater for 70.3). There are also many independent half-ironman and iron distance races that are the same distances as the WTC races but are not part of the race series and do not act as qualifying races for the world championships.

1. Yes, the Ironman 70.3 name is only a couple years old now. Before that, there any race that long was generically called a half-iron, a long course, or sometimes a tinman.

2. No. WTC is a private, for-profit company. USAT is the US national governing body for triathlon. USAT does athlete rankings, sanctions a lot of races, trains officials, holds regional and national championships at the Sprint and Olympic distances, and also organizes the Olympic tri team.

"In 2007, WTC undertook expansion in producing Ironman events internally, with the inaugural Ford Ironman Louisville. This followed the launch of Ironman 70.3 events in Boise, Idaho and Providence, Rhode Island."

http://en.wikipedia.org/wiki/World_Triathlon_Corporation

Wait, the WTC "produces" events too? Meh. I thought they only licensed.