My guess is that no to the first, since I have a 1/3 chance of being in the forked path, vs 1/15 of being in the straight path and my lever being connected.

Suppose you live in a kingdom where everyone is as selfish as you, and you've seen on TV many situations exactly like this one where people were tied to the tracks - usually one at a time and occasionally 10 at a time. (The villain has been prolific.) You've seen them all follow this logic and choose not to flip their switch, yet out of ~1500 people you have seen in peril this way, ~1000 of them have died. If only their logic had convinced them (and you) otherwise, 1000 of them could have selfishly survived! Doesn't seem very logical to follow a course of action that kills you more often than its opposite.

(If you don't want to imagine a kingdom where everyone is selfish, you can imagine one where x% are selfish and (100-x)% are altruistic, or some other mixture maybe with y% of people who flip the lever randomly back and forth and z% who cannot even understand the question. The point is that the paradox still exists.)

Edit: I can see now how in a 100% altruistic kingdom, where you are the only selfish one and you know for sure that everyone else will logically altruistically pull the lever, it makes sense for you to not pull the lever. Presumably there is some population x% split (44% selfish/56% altruistic?) where your selfish decision will have to reverse. Weird to think that your estimate of the selfishness of the rest of the population has a relevance on your decision!