No. CaddD would mean play a C major triad (C, E, G) but add the note 'D' to the chord. That would also be the same as Cadd9 (D is the 9th ). D/F#, I always took that to mean that you play a D major triad (D, F#, A) making sure that the F# is the base note of the chord.

Now, I've also seen a much more complicated explanation of this type of chord form in a book called "Chord Chemistry" by Ted Greene. According to that book, D/F# could be Dmaj7 or Dmaj7#5. I just think that is way to complicated and quite frankly I have no idea if that book is right or wrong.