What resources should be cached android client

I am creating android client for online store. I wonder what resources should be cached.
I understand that pictures should be cached, because they are the most heavy resources from the web.
What about other resources, such as products, categoris, product description. Should they be cached or it is better to load them all time ?
Should I recreate database hierarchy in the local sqlite database ?
This allow user to use the app without connection ?
I am consuming data from the site with REST API. Please suggest the right approach to use here ?