Here's a supplementary episode to answer some questions sent in - they were hard but fun, so keep the questions coming! Sadly, my brother was over so we did it in a different format. It rambles somewhat. But hope it at least answers the questions.
Also let me recommend a book about language - 'The Adventure of English' by Melvyn Bragg. It's a brilliant book, really easy to read.
On a slightly different topic, if you want to understand why the English behave as they do, then there is only one book to read amongst the plethora of books on the subject. It's by Kate Fox, and it's called 'Watching the English' . Suddenly, I understood it all, at last.