Agnetha Fältskog talks about her years with ABBA and her new solo career; Chimamanda Ngozi Adichie nominates Tutu, by painter Ben Enwonwu, for Cultural Exchange; soprano Angela Gheorghiu reflects on her work and her controversial reputation; actor Kwame-Kwei Armah discusses his new role as artistic director of Center Stage theatre in Baltimore; James Hamilton-Paterson discusses his new book, set during the height of the Cold War.