Sider’s “Time Travel, Coincidences and Counterfactuals”

Sider talks about might-counterfactuals of coincidence and would-counterfactuals of coincidence. What are these? Why do we think that would-counterfactuals of coincidence are never true? Why does Sider think they are, at least sometimes, true?

If we all tried to travel back and make the past different than it was, we would all fail. This surely sounds like it means that our freedom is limited, that once we travel back in time we no longer have free will. It is determined, it seems, exactly what we will do in the past. Sider disagrees. What are his reasons for disagreeing?

What exactly is a permanent bachelor? How does Sider’s analogy run between permanent bachelors and time travelers?