Include conference papers with/without proceedings in CV I have papers X and Y published. Each of those produced papers Xc and Yc for different conferences. Xc was presented in a conference with proceedings while the conference of Yc didn't have proceedings. Both Xc and Yc are published in the arXiv and have my name on it as I'm one of the authors in X and Y. However I did not give any of those talks.

My question is do/should I include these papers on my CV? If affirmative, under which section and how to specify that I didn't give the talk.
On my CV, I have a section called Conference Papers, where I highlight the papers for which I gave the talk by underlining my name in the list of authors. You can definitely list these papers, as you contributed to them. Drawing positive attention to the papers you did present probably gives a better impression than highlighting papers you did not present.

Another way to list the conference papers once they have appeared in a journal (or are accepted), is to simply add a note to the journal publication with the conference information.

The customs for conferences with and without proceedings vary. Some researchers separate these into different categories, while others do not make this distinction. Essentially, it's up to you. Researchers who are familiar with your field will know the relative merits of these venues regardless.

Disclaimer: I'm in theoretical computer science, where conference papers count as publications. Fields that place less value on conferences might have other customs.