Facebook timeline – none of the comments or likes on friends posts show on the timeline

Are you referring to your News Feed (Top News), News Feed (Most Recent), or the Recent Activity on your profile?

I think that News Feed (Top News) only displays what Facebook considers to be most interesting to you, so I wouldn't expect your own likes/comments there. The News Feed setting that you mentioned applies to the Most Recent setting.

News Feed (Most Recent) does not display individual stories for comments and likes on posts; you would only see them under the corresponding post, if it is expanded. Are you saying that you expanded the likes/comments and you can see comments from other people but your comment is not there? Sometimes it takes some time for it to show up although it shouldn't take days (unless it was deleted).

If you are referring to the Recent Activity on your profile, there is an additional setting for that that you didn't mention. On your profile's Wall (not your News Feed), scroll to the bottom and click Edit Options. If you have hidden any kinds of stories from your Recent Activity these will be listed and you can unhide any of them by clicking the X and then Save.

As for the Photos tab, that used to be a known issue although the link to Facebook Help in that answer does not seem to work now. I don't know if that means that it should be fixed.

Just get people to go to their messages and see if the offending comments showing in their timeline show up there. I can guarantee they won't. Because they now have timeline they can't go back and check their old wall posts so they assume the things they posted must have been private messages but they weren't. People used to post back and forth between their walls all the time before Facebook messaging became more widely adopted.

Anyway, as I said easiest way to check is to actually look through their messages. I did just that and none of them are appearing on my timeline.