As for "God forbid," it has been explained many times. It is found seven times in the O.T.:
Actually it is found nine times in the Old Testament and 15 times in the New Tesament.
"God save the king" is a paraphrase that is found in 1 Sam.10:24,16:16.
" Gave up the ghost"is found numerous times and is certainly not a word-for-word translation. An example is found in Gen.25:8.
"Cast the same in his teeth" is a paraphrase found in Matt.27:44.
The KJV has indeed a number of paraphrasic wordings throughout its pages.