Regarding #3, Bruce R. McConkie wrote in Mormon Doctrine that “only under the most extraordinary and unusual circumstances” would cremation be consistent with LDS teachings, but I have heard other GAs have said it is ok. In some countries, the law requires cremation. I wouldn’t consider this extraordinary, but perhaps he would….
I have a new book on the Development of LDS Temple worship by Devery Anderson. I know there is some information in the book about dressing endowed members in temple clothes for burial, and I will try to look for more information.
I think consecration of a grave is similar to a baby blessing. It is not a saving ordinance either, but rather is a nice blessing that the church would like to keep under the direction of the priesthood.