If I marry a Japanese citizen, but we plan to spend most of the year living in the US,
Can I apply for spouse - work visa in japan?
Or, do we need to spend a certain amount of days per year
In Japan to be eligible for such.

Well, I don't know for sure, but this (http://www.mofa.go.jp/j_info/visit/visa/long/visa10.html) doesn't say that you can't work.