Crystal affix or mythic affix onto a legendary?

As the title suggests, can you put a crystal affix onto a legendary or add enough sockets to a legend to add a mythic affix? Or do you have to enchant it backwards? That is to crystal a rare item with sockets and then mythic affix it and apply the set affix suchnas spiritmancer to it?

Yes, you can apply them to legends. You just need to remove affixes first to make room for what you want to add. Everything is enchantable except for Eternals.