** Currently my dryer does not vent to the outside. ... is it possible to buy a window with the vent already installed so all I have to do is hook up the hose? **
It may be possible although I think you'd have a hard time finding one to fit the exact measurements of your original window and have the vent hole already in place in it.
It would likely be simpler to find a new window and have it modified to have a hole for the vent put in it before installation. It may be possible to replace one pane of glass with clear Plexiglas so you don't loose much light.
BTW. You should read the following link about dryer vent length.