How an Alternate Signal Travels in a Wire..??

That is a sort of broad question but here are some answers which will most likely raise more questions 0.o

If you know the direction of magnetic lines- you can surmise the spin of electrons of most of the electrons traveling through/over a conductor (fairly new science news). Since alternating current produces opposing field orientations of similar strength in copper coils we can tell that the general paths taken are in reverse. We also know that copper is highly spherical- and that energy does not travel through an atom, it travels across its skin which is like a shell (also fairly new science info). So it must take a somewhat helical path through copper to go in any general linear direction (as when you clump spheres together they interlock and offset) Aluminum wire might be different but surely similar. the loss in efficiency can almost certainly be explained by some of the energy is being used to cancel out the field due to geometry and quantum mechanics of the material. This also explains a bit into the phenomenon of superconductors and why their properties vary widely by temperature (as temperature effects the geometry of the material)

Increasing the frequency of AC gives it a better ability to penetrate a volume in respects of voltage/time. In a plasma I am not sure the electrons may move straight or in an arc- and same goes with the positive matter in plasma, they are free to move around unlike in a wire. But in general the path of least resistance is across the surface- and that path will be dictated by physical properties of the matter

Do not forget the "skin effect" which brings EXACTLY the contrary of what you write!

"Increasing the frequency of AC gives it a better ability to penetrate a volume in respects of voltage/time"

Much of this has already been covered here: Electricity Travels In or On the Wire?

http://www.google.co.uk/search?q=american+amatuer+radio&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GZEU_en&redir_esc=&ei=4ll6TJ3KL4qN4QbkyuSiBg

http://www.google.co.uk/search?q=surface+voltage+on+electrical+wires&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GZEU_en&redir_esc=&ei=Qlp6TN3_Mcyl4QbR6uijBg