Short answers, pulled from the story.
Toyota Center cost $235 million to construct. The city of Houston paid $182 million, the Houston Rockets contributed $43 million for additions and enhancements, and Toyota paid $100 million separately for the naming rights.
Rockets owner Leslie Alexander personally requested the sunken design so that fans would not have to walk up stairs to reach their seats. Sinking the arena required excavating 31,500 cubic yards of dirt over four months at a cost of $12 million, the largest excavation in Houston history at the time.
Toyota Center officially opened in October 2003. The first event was a Fleetwood Mac concert on the 6th of October 2003, and the first Houston Rockets game followed on October 30 against the Denver Nuggets.
Toyota Center seats 18,055 for basketball as of its current configuration. Earlier configurations ranged from 17,982 at opening in 2003 to a peak of 18,430 between 2007 and 2012. The arena can also seat 17,800 for ice hockey and 19,300 for concerts.
Houston voters rejected the arena proposal in 1999 by 54%, following an opposition campaign led by Chuck Watson, owner of the Houston Aeros and the Summit arena. Watson argued the project was "not in Houston's interest." The arena was approved the following year when a revised proposal, emphasizing no new taxes, won 66% of voters in November 2000.
The concert attendance record is 17,962, set on the 20th of November 2008, when Metallica performed during the Death Magnetic tour. The basketball attendance record is 18,583, set on the 26th of March 2010, when the Los Angeles Lakers defeated the Houston Rockets 109-101.