Ok, this is too interesting for me to simply leave for later. I don't know how much I can be of help on this, but I will try.
Jiva wrote:
Q1: What was the Norse relationship between body and soul/spirit? Were they seen as separate or one and the same?
Agreed. A very tough one.
I do think that in some ways these could be seen as separate- if one takes the example of a fylgja being able to adopt another one in the family as "theirs". Problematic with this is, is the Fylgja a being that is a part of you, or something that comes entirely from the outside? I tend to think the former. I have some pages of the subject of fylgjur that I would like to scan to you, but every time I come here to do that, the computer with the scanner is occupied. I did, however, email these questions to both Freyja Aswynn and Vincent Ongkowidjojo, as they might know more.
There is, like you say, suggestions that the soul (or some part like this) remains in the body after death, and therefore, the dead can be re-animated, such as the case probably is in Völuspá, where Odin raises the seeress- whom I believe is dead, in the mound, or either, in Hel or a similar place.
However, I do think that there are also occasions where there's creatures more like "zombies", who do not have a mind as such. But I have not read about this really, just a few mentions here and there. The hungry ghosts, or some such.
Perhaps there is a time limit as to how long the body and soul / spirit remain intact? Or perhaps some parts stay with the body that can answer to certain type of questions but are not really functional as people anymore.
It's difficult to compare burial customs as apparently these varied greatly from one town to the next. I recall from a lecture that one woman's jaw was replaced with that of a pig's, and she was dressed in finery. I don't recall if she had a staff or not. So it's definitely very puzzling to try and make sense of this kind of things. It might be a possibility, that people who were into Vanic worship were buried, and the Aesir folk were burned. Here I speculate in a most gross fashion, and I have no evidence to support this theory whatsoever. Apologies. However, people found with staves are sometimes buried with a rock on their chest or some such, I wonder, was it a acute fear that people with magical abilities might be more prone to rise from the dead?
My personal experience from what could be described as berserking, was that the human consciousness gets completely run over by the animal mind, or instinct. Granted, this has happened only once majorly, but I definitely was unaware of being a human throughout the short but intense experience. The body also seizes to feel like that of a human (one believes it is shaped like that of an animal), and the strength and speed of the animal in question is there. I do not know if this would be a fylgja possession, but I think it probable.
Another thing would be a working where one sends part of themselves out and during this time their mind goes out, and the body lies sleeping or dead-like. This differs from the example mentioned above, as then one certainly is very alert- up and running so to say. I should think that the human consciousness takes a step and hides in the shadows when berserking, and during a sending (as I think perhaps has to do with the sámi tradition, finn. "loveen lankeaminen") where the shaman or witch lies in a death- like state, the mind can move on another levels. This is a more common way of working, I believe, and one that shamanic techniques train towards. As to what sort of results one can make depends a lot of the skill level of the shaman and the depth of their trance state. I'm rather poor in this- but then again I have not attempted to affect to other people.
I do think that wounds inflicted on this state would be wounds on the spirit or soul rather than on the actual physical self. This would affect the body. We can fall sick, for example, if attacked via magical means.
When berserker moves on the physical realm, the other working focuses on working on different planes.
A runic correspondence for such workings, Ehwaz. Corresponds with Hamr, or so I understand. Might work for both physical and astral.
Jiva wrote:Q2: How did the various Norse concepts fit into (or around) the human body?
A icelandic rune poem goes as such;
Reið er sitjandi sæla
ok snúðig ferð
ok jórs erfiði.
iter. ræsir.
[Riding] is a blissful sitting;
and a swift journey;
and the work of the steed.
Journey. Worthy Man
trans. Chisholm
However, the first line can apparently be translated as 'the seat of the soul', which might relate to prophecy workings, horses relating to hamr, or fylgja. This Anglo Saxon charm I am unfamiliar with.
It might be helpful to look into both into sámi and finno-ugric traditions. There's quite a lot of information of horses and horse-related magic- such as nightmares. This would be another example of a seidr- working (?) where the sorcerer sends his form out to do nasty deeds.
A further thing in sending would be the Nithing pole (ON níðstang).
Would the sorcerer send a part of themselves as a shape of a horse, or is this the spirit (lacking a better word) of the dead horse doing the deed instead? If the former is in question, does the horse hide work as a mask of sorts, or is it there for purely psychological terrorism?
I don't know exactly what sort of things interest you- are you strictly into Fylgjur now? Perhaps some studying of seidr material would be useful on the side?
I'm sorry I'm not more helpful at the moment!