Conditional sentence structures in English:

1. If I had X'd, I would have Y'd;
2. If I X'd, I would Y;
3. If I X, I will Y.

Possible structures in Japanese (I got most of these from Google):

1. Xしたら、Yすることはなかっただろう；
2. Xしたら、Yしなかっただろう；
3. Xしたら、Yしないだろう；
4. Xしたら、Yしない。

Are these 4 correct? How do they differ, and how do they line up with the English ones?

If I wanted a "bare conditional" like "I would X" or "I would have X'd", could I take 1-2-3 and suppress the -tara part?