I haven't read the whole thread as it is too convuluted and I have better things to do with my time.

But, just for fun - here's my take on it (apologies if this solution has been discussed before).
Assuming I know none of the people in both cases - in the first scenario I would probably SHOUT at the idiots on the trolley to JUMP OFF and take their chances, because they are more likely to survive jumping off a speeding trolley than going over a cliff (assuming it is a deep cliff that is)...
It seems to me all people involved seem pretty stupid - the 6 idiots on the trolley for not doing something pro-active, and guy number 1 for walking on the fucking tracks in the first place! But just in case I missed some feature of the track that prevents people jumping off, sorry 'trackwalker' but you are mincemeat for being so dumb as to walk on the tracks in the first place (unless you were hoping a trolley would run you down, in which case I have done you a favour)...
In the case of the second scenario, I wouldn't push fatty onto the tracks because he isn't doing something stupid or irresponsible - he is just watching it unfold like I am! So the people in the trolley are on their own in case 2 - though I would, as a responsible citizen, call the authorities, try to help in the aftermath, etc...
Actually, in hindsight - I'd probably do the same thing with regards to scenario one and leave the 6 to their fate - because healthy self interest would make me hesitant to intervene. After all, I might get charged with manslaughter for killing the guy on the tracks, or at least sued by his family! Hehe.
HS!