Questions about the USADA

According to their web site, they are "the official anti-doping agency
for Olympic, Pan American and Paralympic sport in the United States".

Who finances the USADA?

If they are the official anti-doping agency in the US, what give them the
right to intervene in a French sporting event?

What other athletes have they accused or convicted?

Do they run test on MLB, NFL, NHL, NBA, PGA, players? How about NASCAR
drivers? If not why not?