Arrays, Copying and Views. Can someone explain this to me?

You didn't come across as abrasive at all - JavaScript has caused a few profanity-laden exclamations from me too :)

The only frustrating thing about typed arrays is:

var a = new Uint8Array(10);
var b = new Uint8Array(a); // data copied
var c = new Uint8Array(a.buffer);  // data not copied

StringView would make a lot of sense actually - or some way to get strings from a uint8array. I've actually added E.toArrayBuffer for strings so the simplest way might be to add the reverse function too though.

In terms of adding to ArrayBuffers, what I tend to do is:

var source = new Uint8Array(...);
var dest = new Uint8Array(source.length+3);
dest.set([1,2,3]);
dest.set(source, 3);

Having said that, I wonder whether SPI.send/I2C.read/etc would benefit from being able to take an arbitrary number of arguments. It might make the code simpler in a lot of cases.