You still need to make an ADR for Hoop Dee Doo, and pick which tier of seating you want. Without the DP you'll also pay for your reservation at time of booking.
When you make your Fantasmic Dining package you need to tell them it's for that package and then they will tell you what times are available for meals. They tend to be afternoon (2-4pm) times though, so be aware it won't be normal dinner time. Then you arrive at the F!DP entrance (by Tower of Terror) about 45 min before the start of the show.
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My Previous Trips WDL 1990/1993/1996 :: WDW Aug 2003 (offsite) :: WDW Oct 2008 (offsite) :: WDW Oct 2009 Pop Century :: WDW Dec 2009 ASSports :: WDW April 2010 AKL-Kidani :: WDW Oct 2010 ASMovies :: DCL Oct 2010 Western Magic :: DCL Sept 2011 Bahamian Dream :: WDW Oct 2011 SSR :: WDW March 2012 OKW :: DCL Sept 2012 NY to Canadian Maritimes Magic :: DCL June 2013 Alaska Wonder