If I post a picture on Facebook and choose from my smart list, will that picture still be visible to everyone else? And if they like my photo, will their friends be able to see my picture if they aren't my friends on Facebook?
Question: Who can see my post which the audience is a smart list? Answer: the people from your smart list!
The post (an image in this case) will only be visible to the people into the smart list(s) you've selected (your friends).
The like and comment updates to your post, again, will only be visible to the people into these lists (still your friends).
By setting the visibility settings of your photo to a Smart List, you are restricting its visibility to only people on that list. However, it will also be visible to anyone whom you have tagged in the photo who is not on the list, as well as, possibly—depending on your general privacy settings—anyone on their Friends list.
A photo not otherwise visible to someone does not become visible if their friend has Liked it.