 McGilvray 1999 and Smith and Allott 2016 both offer clear introductions to Chomsky’s philosophy of language and linguistics, including his E-/I-language distinction. A shorter account of his views on this topic in particular can be found in Bezuidenhout 2006. Critical discussion can be found in five collections: George 1989, Otero 1994 (Volume II), Antony and Hornstein 2003, Barber 2003, and McGilvray 2005. Chomsky’s own non-technical writing is usually accessible. Good starting places would be the second chapter of Chomsky 1986, the essays in Chomsky 2000 (some of which also appeared within his 1995a), or the early sections of Chapter 1 of his 1995b (co-written with Howard Lasnik).