The lethal fire/acid damage and the disintegrate vs. Regeneration wasn't an issue for me, but thanks for looking it up.
As for the bleeding troll thing...
[...]
Note, it doesn't say he takes one point of damage, but rather that he loses one hit point. This isn't converted to nonlethal, because it isn't damage, it is an effect of the dying condition.
...the underlined part sealed the deal for me
Also, we could interpret it as an "unnamed loss" of HPs and not damage "per se", which would also be valid in this situation.
Just for kicks, i thought of mentioning a tactic we used a few times against trolls in my gaming group, when firepower and acid sources were scarce:
Step 1: Carry a barrel full of water on the party wagon
Step 2: beat the crap out of the creatures
Step 3: Repeat step 2 until they're KO and then some more for safe measure (i.e.: precious time to perform next steps)
Step 4: Drown the creatures 1 by 1 by dumping their heads (still attached to the bodies) into the water barrel
Step 5: Collect encounter XP and go on adventuring...
Note: Also works for aquatic trolls, by dragging them out of their element...
This got me thinking... Would a "Create water" spell work to cause the effects of drowning, if it was cast inside an unconscious creature? I guess it would, since an unconscious creature is considered "willing". What say you?