Do you believe that gods exist on a level of reality stronger than metaphor or archetype?
Yes, I believe that Deity truly and literally exists. Although I am what is often called a soft polytheist, I view my Gods as much more than metaphor. I see all Gods as part of a single whole.. Just because there is Ra, Amun, and Amun-Ra, who are all part of the One, doesn't mean I think they exist any less.
If so, what reason is there to exclude some gods from existence while embracing others? In other words, if you worship the Greek pantheon for example, why exclude the Norse gods?
I do not exclude them from
existing. Just because I worship the Egyptian pantheon does not mean I think the Greek or Norse Gods do not exist. Why I worship one pantheon, and even more specifically why I am devoted to specific deities within the pantheon, rather than all of them.. well, that answer has a few parts. First, a rather simple one.. If I tried to be devoted to every God in a pantheon, let alone every God in existence, well.. I'd have no time for it all!
The Egyptian Gods are the only ones who have ever spoken to me. I originally tried to worship the Greek Gods when I became a pagan, no go. I have tried to follow other pagan Gods, and other non-pagan Gods for that matter, with out ever hearing a peep. My Gods came to me, they chose me, I think it would be foolish to ignore them.
I believe the Names exist because the majority of humans can not fully understand, let alone begin to know, the vastness of the One. We are drawn to Gods to have a relationship with the One. We learn from Deity through it's many faces. Why we are drawn to specific Deities, why some come into our lives and others never do, why we learn the lessons we learn.. well, it's all different answers depending on the individual, and we may not even know why some of these things happen in our own lives.
Again, just my beliefs. Some pagans do worship from multiple pantheons, or have other reasons for following a specific pantheon. Some do not feel that all Gods actually do exist. But, they will have to answer for themselves.
Moreover, if you believe that all gods are equal, why call yourself a pagan rather than a Hindu, since Hindus subscribe to the universalist notion of the equality of all religions too?
This is a bit like asking why Muslims just don't call themselves Jews. Islam and Judaism both have the same concept of God (monotheism), and they have some other beliefs and practices in common, but they also have their differences. So it is with Hinduism and paganism. There are many things which Hindus believe that I personally do not believe. I often do not practice my religion in the same way. Also, not all pagans do believe that all Gods are one, or that all religions are equal.