DB draft

It's been a busy few months so I haven't had time to do any more tailoring but I'm keen to get going again!

I was just wondering about how to modify the draft for a double-breasted coat. Is it as simple as adding a few inches to the front edge? (I believe a peaked lapel is also conventional.)

I was also wondering how the canvas is modified, particularly the horsehair – both in terms of placement and size. If it's a lot more complex than single breasted, then say, but I'm up for a challenge!