The person who hard-linked this node hasn't created a writeup at this time so I guess I will. :)
The concept of a mind is something of an abstraction, an emergent property. A person's mind is more than the sum of neurons, axons, dendrites, et cetera in that person's cranium. Assuming that a mind can survive without a body, perhaps on some sort of astral plane (or maybe even in this plane of existence), it would probably be composed mostly of energy. Maybe someone more versed in reincarnation can shed some light there.
The primary task of the human mind appears to be that of assuring the survival of the human body as well as the survival of itself. From that task stem other tasks, such as eating, bathing, helping allies, and writing Vogon poetry. Without a body to look after, the mind could probably dedicate a lot more of its resources to improving itself. It wouldn't need to sleep much, if at all, since it wouldn't have any organic component that needed to restore its own equilibrium.
A mind without a body would be immortal to the extent that it could avoid corruption of its energy stores and patterns. Energy, like matter, can neither be created nor destroyed - only converted. The cells of the human body have a built-in autodestruct mechanism; they divide a certain number of times and then stop dividing. Therefore a human will eventually die from a lack of new cells, assuming that sickness or physical destruction doesn't cause death first. A mind without a body wouldn't have to worry about this. It would have to have a way of protecting itself from external forces that would add, remove, or alter its structure in harmful ways, and it would have to be able to allocate more energy to store more information as that information was gathered, either from the outside world, or as the results of its own internal thoughts.
Such a mind would need to be able to imagine, to simulate, to hypothesize. It would need a great deal of this ability, because without it, it might as well just be a memory store. It would also require sense channels and some method of manipulating the external universe. Failing that, the ability to survive and maintain a vast simulated universe for it to explore would be vital - like Vishnu.
A mind without a body would not confuse elements of the body with elements of itself, for the simple reason that it wouldn't have any physical traits such as height or weight or gender or eye color.
I'd like to see other people's writeups of this, maybe we can get a metanode going! I'll bet there are as many ideas on this subject as there are e2 users.