Facebook – View liked posts by friends’s friends

Facebook is intentionally vague on this issue. See here

Normally if it doesn't appear on the timeline, it will not appear in a news feed. So, if you choose not to share something and it doesn't appear, it won't go to news feed. If it does, however, come to timeline, you have to implement the audience control.

What you need to do is see if it shows up on your timeline. If it does, you can delete it or change the audience

If in doubt, always turn on timeline review to stop things from getting through.

No. Only your friends will still see the picture.

Any comments on an item inherit the same privacy as the original item, and never change the privacy of the item.

If your privacy setting for pictures limits the visibility to only your friends, the friends of your friends won't see it, or any comments on it.

However, if they are also your friends, they might get in their news feed either the picture, or a mention of your friend's comment on the picture (depending on what the omnicient holy Facebook Algorithm determines they want to see).