Android "Best" way to implement button callbacks (XML onClick, New onClickListener, implement onClickListener, seperate class for that button)
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This is my first question here guys, I've finally registered because I've popped in so many times I felt I was actually making it worse for myself. This question is quite open ended yes because I want the pros and cons. 
I've tried to EMBRACE Android and how it does things (XML, Activities, destroying Activities) stuff like that, and normally I'm a WxWidgets man so this feels very different. The more I read the more it makes sense. But there is one question, this question, which applies not just to buttons but all callbacks. Android Tutorials and guides so far seem to be (MOSTLY) more about getting something running quick, as I said, I seek to embrace Android, not make yet another tat app for it.

So as the title suggests I've used buttons for this, but yes, any callback.

First usage case "Question"
Consider 2 Fragments, A and B, and 2 Activities, X and Y.
Lets now say A contains a list, and B the details for an item on that list (a generic setup)
If in Landscape mode Activity X will display both Fragments, A and B, if in portrait mode, if nothing is selected (and the selection stored via whatever means (feel free to mention potential/decent ways) Fragment A will be shown by X, when something is selected (or if something was selected) Fragment B will be shown by Activity Y.
If it is in landscape mode, Activity Y will have it's "finish()" method called, which I understand commences it's destruction.

If I use the XML onClick method, B will sometimes get that callback, if it is finished, how can it, will it go to A instead?
Should I add the logic to the fragment? (by making a new onClickListener inline)
Should I instead do what I'd probably do in WxWidgets, where I extend a class for basically everything and have my own class for the button, which implements onClickListener and hence can have it's own onClick method?

If it helps in my homework I have learned that I probably shouldn't try and catch the config change events, I accept that my Activies will be closed and restarted, so I can in the onCreate methods check the orientation because for the lifecycle of the activity it won't be changing orientation.
Which leads to my final question, is Bundle the only way? I found another, but it was deprecated and only for config changes.

Thanks, sorry it's long and yes, quite broad. I truly cannot find a debate on this anywhere.
(In the post today arrived the O'Reilly Android book, I suspect that they (O'Reilly books) are popular here, please give me a page reference or even what this is all called if you know. The Wrox Android 4 Dev. book also arrived I had this as a PDF and to show my approval, purchased it, again, subject title please this is 4th edition (or just 4) so I have yet to read the Fragments section but I doubt that'll shed much light)

BTW, I can see the similar questions down the side and I been reading them when I click post on this, if I do, it is because I still see this as a question. 