Believe it or not, it's common that the PS fluid clamps need tightening on ALL newer Volvos ('99 on up), not just S80s and that's not your dealers fault. We see that problem daily. I also highly doubt that PS fluid shorted out your alternator as I've NEVER seen or heard of that even though we often see alternators dripping with PS fluid. One can even wash alternators with water and they don't short out from that either so that theory is untrue.
As for your other S80 problems, for a '99/'00 those are also not ununsual and there are many more costly problems to come, many requiring the dealer only Vadis PC for software. There are good reasons why many early S80s are sitting on used car lots. Read consumer reports on them if in doubt.