Is the last part about C/C++ correct?
No, it's not.
Some languages do compile to C, but that's not specific to functional languages. If this is more common among functional languages than non-functional ones, it certainly isn't so to the extend that one might call this a property of functional languages.
Further it's definitely not the case that most real-world functional programming languages are compiled to C (by their official and/or most used implementation). If I list the first ten functional programming languages/implementations I can think of (Haskell (GHC, Hugs), OCaml, F#, Scala, Clojure, Racket, Common Lisp (SBCL, CLisp)), none of them compile to C (to the best of my knowledge). GHC did have a C backend at one point, but that's been discontinued.
Two languages, that I can think of, whose primary implementations compile to C are Vala and Haxe, neither of which are functional languages. In one of the linked threads, Chicken Scheme was mentioned. So that's one relatively well-known implementation that uses C. That's hardly enough to justify the claim that this is "generally" the case.