Special Summons do not use up your 1 Normal Summon or Set for the turn, and can be conducted as many times as possible in a turn (both yours and your opponent's) and if generally referred to, a monster is Special Summoned in face up ATK or face-up DEF position, unless indicated by the card. Special Summoning requires no Tributes unless indicated by the card.
"Premature Burial", "Call of the Haunted", "Monster Reborn", "Soul Resurrection" and "Autonomous Action Unit" can all Special Summon monsters from the Graveyard. Thus, you can activate each card (provided you have enough Life Points) and resurrect five monsters, as well as conduct a Tribute Summon or Tribute Set in the same turn.
Fusion Summons, Ritual Summons and Synchro Summons are all considered Special Summon.