When using Fenians' benefit, do they also add their bomb value?
No.

Page 6 of the English rulebook states under the sub-heading "A Short Interlude About Cards" that,


  In all circumstances a card can only ever be played for one type of symbol on it or
  the text effect described in the text box


When played for their ability, Fenians double all bomb points of cards you played to gain bomb points.  If you had two Fenians cards, you could play one for bombs and one as a doubler.

Hope this helps!