How big (or small) should I be going? I was told 6" wingspan minimum. Yet, most kites I've seen are 1.2-1.4m across. Maybe, it's just due to the sites I've been looking at.
Welcome to the forum Chris.
The majority of trick kites are roughly same width. This is a sweet spot for the weight and agility in most suitable winds and which is dictated by the length of off the shelf carbon rods.
Also, for a standard weight kite, you should just be concerned whether it's ok to fly in 8-12mph. Quoting ridiculous figures like 22mph is rubbish, because you'll never want to be out in that kind of wind unless you intend to break your kite. For a beginner, stick with as light a breeze as you possibly can, so you have time to react and learn.