R. Scott Falk, a partner at Kirkland & Ellis LLP who negotiated multibillion-dollar mergers and acquisitions, died Friday at the age of 55.Falk was the chairman of the Chicago Humanities Festival and a past chairman of the American Red Cross of Chicago and Northern Illinois as well as the national Red Cross’ National Philanthropic Board. Between this and the time he spent with his family, “I have been trying to figure out how it was possible for one person to do all that,” said Sanford E. Perl, a …