Hello there Server-lovers!

I’m calling out for your Professional help regarding some issues that i don’t understand.
For some years i’m administrating a HP Proliant Server, at my office just because nobody  else want to do it.
I’m just an amateur, but Windows Server 2003 is pretty easy to understand.
For some weeks ago i bought myself a HP MediaSmart Server EX475 with 500+500 Gb.
The first thing i did was to add 2 disks with 1Tb each.
I then added them to the Storage Pool, and can see that the Total Size is 2,73 Tb.
So far so god.
I use a HP Workstation xw4400 with Windows Vista Ultimate, and I put up network shortcuts to the shared folders.
And now starts the questions:

1. Windows explorer  shows 445 Gb total space and 445 Gb of free space on each shortcut. Why ???  How is the balancing of the disks working ?
I installed 2 add-ins (”Disk Management” and ”Advanced Admin Console”) to figure out
where my files are in what partition and so on…  (just have to know)
(And just for the record: I turned off duplication of folders because i still have my Maxtor 1 Tb Lan-disk to  backup my media files to.)
When i dug deeper into disk management i discovered this: I have 4 disks.
A System disk with 2 partitions of 20+445 Gb. They are named C: and D:
The second 500Gb disk and my 2 extra 1 Tb disks has no unit letter assigned.
Insted under ”Shadow Copies” they are marked as C:\fs\I\, C:\fs\G\ and C:\fs\H\.
Is that OK? Is that a part of the balancing / raid system ?

2. All of my media-files (some 460Gb) has been copied to the 500Gb disk with no letter assigned (C:\fs\I).
That means that the disk is 97% used.
Is that really a good disk managing?
I can’t defrag files, simply because there isn’t enough free space.
Can i move shared folders, or divide them to my bigger 1 Tb disks ???

3. Now to iTunes:

This is how i used iTunes before HP MSS:
Because i synchronise both a iPod and a AppleTV, i stored all my music on my Maxtor LAN-disk, (almost 100Gb of music) with a playlist in iTunes for each and every album.
To share these playlists i used to administrate iTunes in our family and stored all MP3-files on the Maxtor disk. In my backup-rutine i then copied my iTunes-folder to each computer (3 in our network).
Do i have anything to gain, if i would let the MSS administrate iTunes?
I would have to gather all my MP3-files to my local iTunes-folder on my Workstation, and then share it again on MSS.
Then each of the family members could create their own playlists, and everything would be shared on MSS.  Is that wise?
When i have local playlists i can show Album covers, but i’m not sure if that is the case when i use a shared folder in a network.

Many questions from a curious guy.
I really hope for someone to take the time to read and solve some of my problems.
Many, many thanks in advance!!!

Smajo