Is it correct that if nothing is recited in the third and fourth raka't of Fardh Salaat, the Salaat is valid.

Answer

In the third and fourth raka't of a Fardh Salaat, the Salaat will be valid even if nothing is recited. However, one should recite Surah Faatihah if one is a munfarid (that is, performing alone). But the Salaat will be valid even if the munfarid does not recite anything.