Yes, monsters may be 'tribute set'.
Yes, the monster obtained by the effect of Creature Swapcan be tributed.
You would miss the timing to activate the card as the monster sent to the Graveyard must be last thing to happen. During a Tribute Summon, the monsters are sent to the Graveyard, but the last thing to happen is no monster being Tribute Summoned.
Yes. Face-down monsters can be tributed for tribute summons, card effects, etc.
You need one tribute for a Lv5 or 6 monster, and two tributes for Lv7+, though many higher level monsters have additional or different requirements.
You can only ever tribute monsters that are on your side of the field, unless a card specifically lets you. Cards like this are Soul Exchange, and Lava Golem.
No, you can only use you're monsters for Scrolls Of The Six Samurai. You can never tribute something you don't control.
Yes you can, Soul Exchange simply offers a monster on your opponents side of the field as a tribute, as well as any others you may control.
Level 7 or higher monsters can only be tribute summoned by tributing 2 monsters, unless a card condition allows it such as Moisture Creature or Gilford The Lighting or the card condition requires it such as Victory Dragon. Yubel only needs two tributes.
Yes, you can activate Torrential Tribute whenever a monster is summoned. Here's a hint you can also activate on your turn to destroy your opponents monsters.
Unless specifically stated otherwise, a tribute (and indeed, any cost) must always be something you control. Soul Exchange and Lava Golem let you tribute the opponent's monsters. But there is no need for cards like the Wicked Gods to state the tributes must be your own, as that is the default and needs no further explanation.
By their Effects, you can Tribute the following monsters by themselves to Tribute Summon monsters above Lv.6 of the corresponding Attributes:Flame Ruler - FIRETrojan Horse - EARTHWhirlwind Prodigy - WINDFor examples, you can Tribute 1 Flame Ruler to Tribute Summon Firestorm Prominence (a FIRE monster, Lv.7), and you can Tribute 1 Trojan Horse to Tribute Summon Raging Earth (an EARTH monster, Lv.7).
A Tribute must be a monster you control, unless specifically stated on the card. Cards like Soul Exchange, and Chimeratech Fortress Dragon, specifically let you use an opponent's monster. But Malicious Edge does not say so, so normal tribute rules apply.
Yes, you can.
Yes, monsters may be 'tribute set'.
Yes, the monster obtained by the effect of Creature Swapcan be tributed.
You don't need to sacrifice (tribute) any monsters to summon a level 4 monster. Level five monsters require one sacrifice.