Buy Cadillac STS Seville 32V Northstar or not?

Good evening to all together, I have a (I think it at least) great offer for a Cadillac STS Seville 32V Northstar Bj. 95 and would have asked a few questions, which I hope can be answered here by a few US car professionals. Since I have no experience with US cars or Cadillac yet I wanted to clarify a few points before I decide to buy it. So now the questions I would have: Where is the consumption with the car? How expensive is the insurance and tax? What should I pay special attention to when I go test driving? Are Cadillac’s vulnerable cars? (I don’t believe it ;-D ) …. I think that’s all I’m interested in right now. I hope I can expect answers and good tips from you soon and thank you in advance. MFG