Re wages
yes, more than national average.
Are you ever not writing, or do you finish a book and start the next one straight away?
It's a bit more complicated than that. If you're on a book a year schedule, you will be writing a first draft, editing the previous book, and promoting the one before that. Generally, I am doing all of these things. But I do take a couple of weeks off after delivering a book and then I take a few weeks to plan the next novel, too.
Also, how many hours a day do you write? On average, how many words do you write a day?
When writing a first draft, probably 3 hours a day and the rest is responding to readers, admin, publicity - writing articles or short stories for supplements etc - editing another book, dealing with financial admin.