1. The Federal Election Campaign Act (52 USC 30101) prohibits foreign nationals and governments from giving or receiving money in U.S. campaigns. The Federal Election Commission has made it clear that it is perfectly lawful for foreign nationals to be involved in campaigns, as long as they are not paid and do not donate money. This is murky because while Steele is a foreign national, he wasn't directly linked to her campaign. What is known is that Hillary and the DNC paid big bucks for information against an opponent in an election, which is actually illegal.
2. If they did not actually state the purpose of the money that was spent to Steele and Fusion GPS it falls under another US Code, prohibits the filing of false or misleading campaign reports to hide the true purpose of the money (52 USC 30121).