CS is most often referred to as a home version (like a PlayStation, PlayStation 2, XBox, etc), as opposed to AC which would be the arcade version.
V5 is still in the arcades, and V4 has still not been even announced for PS2. V on the other hand has been out for a while on PS2, and the songs you mentioned are unlockables on V (i.e. Little Prayer, Destructive Wave, Taratta Dance).
Plus, Dragon Blade isn't an unlockable (much less available) on V for PS2. It was available off the bat on all arcade versions since it's release (including V through V5). The only way you can play it at home is to buy Masterpiece Gold.
In terms of releases for game releases, V simply just indicates a renaming of the GFdm franchise series, it doesn't have any other meaning besides that. So the series goes...
Guitar Freaks 1st Mix (GF1)
GF2
DrumMania 1st Mix (dm1)
GF 3rd & dm 2nd
GF4dm3
GF5dm4
...etc...all the way to...
GF11dm10
GFdm V (essentially Guitar Freaks 12th Mix & DrumMania 11th Mix but no longer called that)
GFdm V2
GFdm V3
GFdm V4
GFdm V5
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