I don't know the answers to your questions, and I've never heard of this butter, but I saw you asking a similar question in Nutrition and Eating, so I figured I'd take a shot.
I'm curious as to where you live. From what you've written, I'm assuming that LURPAK butter is available there. Does your country have laws about labeling GMOs? I generally try not to buy the items that are commonly GMO unless they are specifically labeled that they aren't. Generally buying organic precludes GMO, but I don't know if that is true in every situation.
If LURPAK is a European style butter, it probably has a higher fat content than butter that is typically made in the US. Butter in the US is typically sweet cream, although sometimes it is cultured. Organic Valley makes a cultured European style butter. Kerrygold is another brand that is carried in stores where I live, it's a grass fed Irish butter. The other European butter that is available where I live is Plugra. I don't know much about that kind. RBGH-free stuff all seems to be labeled as such with an accompanying disclaimer.
Lurpak has a facebook page, so you could ask some questions there.