Hi Dan,
Good luck with your decision making! I have been in HK for almost 2 years now, and I don't know much about the Graphic Design job market, but I know a bit about the teaching lark!
When my flatmate moved to HK a few years before me, immigration didn't require a Degree to teach. However, now you do. You need to have the minimum of a degree and some sort of teaching experience or qualification.(However small!) I needed to get a TEFL before coming here, and did it in the UK in 48 hours, on a weekend course with a company called i-to-i. (
www.i-to-i.com) i think.
Try coming here first on your 3 month tourist visa, and check the job market out. It's always easier to go through the process whilst your here. And in regards to living expenses, everyone always tell me HK is expensive, but thats not true! Accommodation anywhere in the world can be as cheap or as expensive as you want, you just have to look! You can find small, but nice accommodation anywhere here anywhere between $4- $40!!!
Hope that helps a bit! Check out the HK Immigration website too. Another website I checked out for jobs is
www.tefl.com and of course
www.scmp.com.
Good luck again!
Dizzy