How tall are you? I would say that a 56 cm frame is usually ideal for riders about 5' 10" tall but as Cyclist33 suggests, you can tweak that with longer (or shorter) components.hope its big enough...
i reckon flat bars would make it a superfast hybrid with the right set-up. i like that kind of thinking - not everyone likes the drops
Flat bars on that frame
I would put a Sram groupo on and intermediate/decent lightish semi aero wheels. See how it rides and upgrade as and when you see fit.
Groupset
Wheels
Alternative Wheels
That will leave you a reasonable amount for seatpost, saddle, stem and anyother minor bits to finish.