Do you mean "1+p" instead of "2-p" at the end there? If not, where does "2-p" come from?

Thanks, error corrected (I mixed up p with 1-p).

Why do you say that (N=2), since the number of individuals is actually random? If you EXIT at X, then the individual at Y doesn't exist, right?

Because the number of individuals is exactly two - in that you have a certain probability of being either individuals. The second may not exist, but the probability of being the second is non-zero.

But I admit this is not fully rigorous; more examples are needed.

Do you think CDP can be formalized sufficiently so that it can be applied mechanically after transforming a decision problem into some formal representation (like a decision tree, or world program as in UDT1)?

I believe it can be formalized sufficiently; so far, no seeming paradox I've met has failed to fall eventually to these types of reasonings. However, more work needs to be done; in particular, one puzzle: why does the CDP for the absent-minded driver give you total expectation, while for Eliezer's problem it gives you individual expectation?