I notice that when I create a breakpoint for small size formats, and remove an image so it's not longer visible at that breakpoint, that it deletes it from the larger view as well (i.e. all together from the site). Am I missing something?

What you want to do there instead Matthew is not to delete it. Instead, select the picture and go to the Design pane and under the POSITION heading, set the Display to None. That will then hide the picture leaving it to show still on higher breakpoints.

http://s11.postimg.org/skzxga2nn/Screen_Shot_2016_02_11_at_12_38_15_PM.png

Very cool. Thank you Scott.

Thank you! This was driving me nuts...