Re: So, to sum up. . .
"The Single Market and the CU are not the same, although plenty of people think they are"
You are completely correct. Specifically members of the EFTA are in the SM not the CU.
They are all in Schengen*, had to draw that Venn diagram in an exam once. EFTA and EUCU are exclusive sets, Schengen and CTA (UK and Eire) are exclusive sets, Eurozone is a subset of the EU which is a subset of the EUCU.
However, I do feel that many Leave voters would feel the same about EU membership as EFTA membership. Notably following EU laws in many areas, EU courts ruling on laws, free movement of people, paying into the common fund, all while not having any MEPs or a seat on the Council of Ministers.
* I say that there are fiddly bits that aren't, but the bloke marking my exam was looking for a less pedantic view, and told me as much in class