1. you can change permissions with the chmod
2. not sure what you mean by this, are you asking how come a regular user doesn't have the power of root???? there is a work around for that if you wanted a regular user to have most of roots privileges..
3. depending on what kind of card you have ??, you can load the modules for it or might need new drivers.. most likely your install already compiled with sound support, unless you marked no otherwise..
4. modules - quick definition: in software a module is a part of a program. Programs are composed of one or more independently developed modules that are not combined until the program is linked. a single module can contain one or several routines.
5. you can always view the man pages by typing man what your looking for
from the command line... example:
that would pull up info on groups.. etc..