Short answers, pulled from the story.
Bill Gates co-founded Microsoft in 1975 with his childhood friend Paul Allen. The partnership grew out of their collaboration at Lakeside School in Seattle and their work developing an Altair BASIC interpreter for the MITS Altair 8800 computer.
Gates became the world's youngest-ever self-made billionaire in 1987, at age 31, following Microsoft's initial public offering in 1986 and the subsequent rise in the company's stock price. His net worth at that point was $1.25 billion.
The Bill & Melinda Gates Foundation, now called the Gates Foundation, was created in 2000 when Gates and Melinda French Gates combined three family foundations with a $5 billion stock donation. It has been identified as the world's largest private charitable organization, with assets reportedly valued at more than $34.6 billion, and funds vaccine programs, efforts to combat tuberculosis, malaria, polio, and AIDS, sanitation initiatives, and educational grants.
In 1980, IBM contracted Microsoft to supply an operating system for its upcoming personal computer. Microsoft acquired 86-DOS from Seattle Computer Products, had it adapted for the IBM PC, and delivered it as PC DOS for a one-time fee of $50,000 while retaining the copyright. When other manufacturers cloned IBM's PC hardware, Microsoft licensed the same system as MS-DOS, making the IBM-compatible PC running DOS a de facto industry standard and transforming Microsoft into the leading software company in the world.
The Giving Pledge is a commitment Gates, Melinda French Gates, and Warren Buffett signed on the 9th of December, 2010, to donate at least half their wealth to philanthropy over their lifetimes. Gates and Buffett founded the campaign in 2010 to encourage other billionaires to make the same commitment.
In a Reddit question-and-answer session, Gates stated that machines will initially do many jobs without being superintelligent, which he considered potentially positive if managed well, but that a few decades later the intelligence would be strong enough to be a concern. He said he agreed with others who found this worrying and recommended Nick Bostrom's book Superintelligence: Paths, Dangers, Strategies at a TED conference in March 2015.