How to setup Oracle Assets Tax Depreciation if Corp book is already worked

My client has only Corp Books but now they want to calculate tax depreciation through the system. I am new at Fixed Asset. So please Help me to set up Tax Book Depreciation. My key points are: I know how to setup Asset Tax Book. But after that did assets categories will also copy automatically at initial copy stage along with Assets in to the tax Book. Second Question how and where to give Tax rates at assets level or at categories. How they will change these rates each years.??

Regards