For string changing on any guitar, but especially a 12- this is an absolute must:
http://www.amazon.com/Planet-Waves-D.../dp/B008BPI2OW
This will save you hours, is very inexpensive, and trust me, it is worth its weight in gold.
I play an older Taylor 450 which I really like. You just can't go wrong with a Taylor 12 string IMHO. I want my setup as low as possible without buzz when I strum fairly hard. For me, this is for all my guitars, not just 12s
Hope that helps.