facebooksharing
Suppose I share a status update with a custom list with a few friends on it. Now if a friend that is on that custom list shares it publicly then will all our mutual friends (some of whom are not on the custom list) and the public in general be able to see my shared (by a friend) status update?
EDIT: I should also add that the default privacy setting for my updates is limited to friends only and only friends can see posts in my 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.
Facebook changed this in September 2011. The first time that you set the audience to specific lists or people after the change, this notice pops up:
Any custom audience set to specific lists or friends after you are shown this notice will show the list of names. If it was set before you were shown the notice (even if the same setting is still being used for new posts) will just show "Custom" as before:
If you don't want it to show the list of names, one thing you can do is post to Custom, choose Friends and under Hide this from enter a friend list or certain people that you do not want to see the post. In that case it will appear to others that it was posted to Friends as shown below; they will not see the list of names that are included or excluded. However, because new friends will not be in any friend list at first, they will see any posts that were posted this way if you don't remember to quickly add them to a list.
Another way to avoid the list of names is to post to one of the automatically generated "smart lists", such as the Family, city, and school lists. Unlike the other lists, where the people do not know which lists they are on, people are placed on these lists automatically based on their own profile information so they should already know which of these lists they are on. In this case the list is shown rather than individual names:
Edit: So in summary, if you set a post to be visible only to Friends, Friends of Friends, Public, or one of the predefined Smart Lists like Family, city, or school, it will show that (no individual names); even if you hide it from some of those people no names will be visible. If you make it visible only to Close Friends, Acquaintances, one of your own custom lists that you created, or to individual names, then it will be expanded to show the people's names (none of those list names are shown); if you hide from some people then the people you hid it from will not be in the list of names.
I don't have a definitive answer on combinations of multiple lists; it seems that there is some way to get it to say "Custom" with some but not all combinations. However even if you figure out how it currently handles multiple lists I would not count on it staying the way it is for long. Facebook is known for making frequent changes to documented behavior, but that is nothing compared to the frequent changes they make to undocumented behavior.
Best Answer
Text Status Updates
If you're just writing text and posting the update to a limited group you'll be at the mercy of copy/paste functionality. The share link doesn't appear for text status updates
Text Status Updates with people
People that you've shared with on your friend's lists will only be able to see it, however, if your with friend has chosen to share posts they're tagged in with a wider audenience then you'll be at the mercy of that setting.
The share button also will not show up here, but you'll likely still be at the mercy of the copy/paste function.
Link status updates (with and without) people
If you share to a restricted list the share button will not appear and your friends will have to tell the story about where they got it from without you.
Image status updates (with and without) people
If you share an image to a restricted list the share will not appear and your friends will have to either post a link to the image or upload the image themselves after downloading it to repost it on their timeline.
Things to consider
Nothing you share with Facebook (even if it's set to only me) should be considered private. Bugs, settings, and future service updates could accidentally/intentionally display this information to your friends; so post with care.