second question; why "Hush! Caution! Echoland!"?

Here Comes Everyman


This page from Finnegans Wake by James Joyce has the triptych of words;
where the capitalization of the HCE runs through as a verbal, graphic and emblematic connection to the character of Humphrey Chimpden EarwickerEarwicker, a nickname given him by the Sailor King, that helps Chimpden, now known by his initials HCE, to rise to prominence in Dublin society as
"Here Comes Everybody",
and as a character capable of overlapping with the qualities of both reader and the author, as for instance;

Marshall McLuhan uses the word Echoland in his amazing late work with Wilfred Watson From Cliché to Archetype (1970) to identify a particular type of space, and its characteristic dynamics, that has current relevance to the spaces of e-dialogue and the the information environment.

Symbolism is the art of the missing link, as the word implies: sym-ballein, to throw together. It is the art of syncopation. It is the basis of electricity and quantum mechanics, as Lewis Carroll understood via Lobachevski, and non-Euclidean geometries. The chemical bond, as understood by Heisenberg and Linus Pauling, is RESONANCE. Echoland. The world of acoustic space whose center is everywhere and whose margin is nowhere, like the pun.

WOW!
The Wikipedia page on McLuhan mentions that:


One major facet in McLuhan's overall framework introduced in this book that is seldom noticed is the provision of a new term that actually succeeds the global village; 
the global theater.