SEO & Keywords Queries

I am slightly confused with SEO and i was hoping someone could help clarify a few things for me if possible.

Is adding SEO Info in say Photoshop, the same as adding it in the SquareSpace Organisation panel or do you need to do both?

I was also under the impression that by importing an image which already has SEO applied to it, that this panel would populate with the keywords that were added to the image but it doesn't.

I wish Squarespace had a copy paste approach to keywords, as manually adding them one by one is a nightmare when you have hundreds of products!

Any help in this area or a better way to do it would be GREATLY appreciated! Thanks!