well seeing as im a n00b to UNIX to i can only answer a couple of your questions..
UNIX is basically the OS for mac os X like DOS is to windows however..its better LINUX is a free upgraded version of UNIX so there almost the same thing.. UNIX can be ussed for many things as a text editor and organizer you can print from UNIX and you can see many things like who has accesed your account and even host mini chats over it. some basics for UNIX you probaly should know are the 4 text editors ( for lack of a better term) they are vi, emacs , ed and pico. They all come with there own cool little things. i like using pico for typing anyways also you should know that the command rm can be used to delete or rename
EX: rm test1 (deletes file test1)
or rm test1 test2 (renames test1 to test 2)
to move around in UNIX you can use the cd command for example to move to your bin directory you could type
cd bin. opening files you should be familer with, to open a file just type open filename
as for all your other questions i do not know the answer to, hope that helps good luck