First off, this is such a heart-wrenching story! And its so well written. For being new to the boards, I admire you jumping in with such a controversial subject.
For the discussion about Clark's form of suicide, I think it fits for him. I'm with those that believe when his invulnerability is down, he is susceptible to most anything just like the rest of us. It would be a pretty clean suicide. Being exposed to kryptonite for so long, added with the ingested kryptonite, would have been enough. The drugs and alcohol was just an added bonus. (Morbid, I know. Sorry.)
I don't think Clark would have gone for a more violent suicide. It was pretty much a sure thing the way he did it. And he was able to die in his own apartment as Clark. Since it was more private, there'd be a better chance that whoever found him would be a friend. That would go a long way to keeping his identity secret. So I bet he did put thought into preserving the Clark/Superman secret. After all, his parents are still alive. Bad guys aren't necessarily a problem, but I can't imagine they'd be left alone in their grief if it became public who they were actually grieving. So maybe the drugs and alcohol were for appearance sake.
Anyway, I think Clark wanted to go as Clark. And he wanted everyone esle to see it that way too. The tape revealing the secret was only addressed to Perry and his parents anyway.
So...I think you did a great job.

This story made me cry, I'll admit it. Especially the part where Lois had already written his obituary and he wanted that to be used. Welcome to the boards and I hope you keep writing!
~Kristen