+1 for Sumatra as a viewer, it's super fast, even with large documents.
Okular has support for filling forms, but I'm not sure if it has more advanced editing features.
A non-adobe, but closed-source alternative is Foxit. It's Chinese, so not EU, but also not US (:
I like the idea, but really dislike the name. Makes it sound like it should follow in USA's footsteps which exactly what we don't want.