"What not", "what have you" and "so on"

Do "What not", "what have you" and "so on" mean the same? Can they always be exchangeable?

For example

A, B, and/or what not / what have you / so on

Solution 1:

"Whatnot" is a single word, or sometimes a hyphenated "What-not".

The three phrases are broadly equivalent, but differ in formality.

• "... and whatnot" -- common in spoken communication, not in formal writing.
• "... and what have you" -- also common in spoken communication. Slightly more acceptable that "whatnot" in formal writing.
• "... and so on" -- equally acceptable in spoken communication and formal writing.

"And so on" is used pretty much universally. The other two would give you some clues as to the speaker/writer's social background, although more complicated than upper vs lower.

Solution 2:

The piece of furniture referred to above originally would have been called a whatnot cabinet or a whatnot shelf, and the "whatnot" refers to the objects displayed on the furniture.

"What not" meaning "other undefined stuff" is two words.

"When the display shows values -- speed, temperature, torque and what not -- does it show the maximum values?"

"What have you" could be used in the same way in that sentence. "And so on" implies more strongly that there are in fact more items in the list. "What not" and "what have you" are indefinite.

My statement regarding one word versus two words comes from a style manual for court reporting probably dating to the 1960s.