The possible answer to all of those questions came to me in the form of Tom DeFalco and Ron Frenz's Thor Vol 1 #400. As you can see here , following Surtur's defeat at the hands of Thor, Odin uses his very own body to imprison the demon. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.