Series 2 VT commenced 06/99. Many parts revisions for the series 2, whih you will find when you call up holden asking for parts. Go for at least the series 2, because the series 1 tail lights look ****
Rear camber problems were prominent in SOME models from VT to VX series 2, where the camber problem was fixed for every car. Not every VT/VX Series 1 had it, some had/have it worse than others, so it is something to look at when you go for an inspection.
As for which model you want to go for, well it completely depends on what you want.
Sports driving, get a manual, get an S Pac.
Luxury, get a Berlina, or a Calais if you are picky and want those few subtle extras and are willing to pay the premium for the badge, by that i mean Calais are generally a fair bit more expensive than Berlinas with not much more features than the Berlina.
So which model you buy depends on what you want and how you are gunna use your commodore.