How many people in the pews know that [ Jonathan Edwards] is both a founder of evangelicalism and, say, an idealist who denied that the material world exists?

In the twentieth century the Reformed tradition was developed in several ways including additional confessions (Barmen, the Belhar Confession, the 1967 Confession of the PC(USA), and so on). It was also significantly augmented by the work of important thinkers like Karl Barth, T. F. Torrance, Jürgen Moltmann, Emil Brunner, Kathryn Tanner, and so on.

[Jonathan] Edwards definitely shows up in the book [Saving Calvinism]. He appears as one of the interlocutors in the chapter on free will, the other being the Southern Presbyterian theologian John Girardeau.

For instance, the notion of non-penal substitution. This idea, found in the work of the nineteenth century Scottish Reformed theologian John McLeod Campbell and based upon his reading of the letter to the Hebrews in particular, is that Christ offers up his life and death as a penitential act on our behalf, rather than as a punishment in our stead.

[ Jonathan] Edwards is the person who really made theological determinism a serious option for Reformed thinkers, and the influence his views had in nineteenth century Reformed thought, in the USA and the UK in particular, is enormous.

I recommend Doug Sweeney's recent book [Jonathan] Edwards the Exegete (Oxford University Press, 2015), which is a terrific treatment of the way in which Edwards was steeped in the Bible, so that it shaped the whole of his thinking.

Jonathan Edwards developed a Calvinistic strand of the doctrine.