Questions about hreflang

Re hreflang - two questions. 1. If you have a website that has a `partner` website in another language - how should pages that don`t have a duplicate page/url be handled? ie to not have any hreflang on those pages? just have a canonical? 2. is there an hreflang equivalent for images that are used across different language domains - I don`t think there is but I thought I would ask.