Forum:De-Fusion VS. Five Headed Dragon

Ok, so I have a pretty sweet dragon deck set up, 2 FGDs, 2 BEUD's, Future Fusion, 2 Gold Sarco's and 8 Dragon Synchro monsters. I've been playing pretty well with it (losses are at around 5%) but I've been scared to try one thing; use my De-Fusion on my FGD. If I do, can I special summon all five of the cards I sent to the Graveyard? And if so, is there's another monster on my field taking up space, is summoning 4 ok? Please help me out here, I've only recently gotten back into Yu-Gi-Oh^.^;