You can set the monster you tributed for, but the tributed monster is sent to the graveyard
Yes, the tributed monster does not have to be face-up at all, it can be tributed while face-down.
Yes, the monster obtained by the effect of Creature Swapcan be tributed.
Yes. Face-down monsters can be tributed for tribute summons, card effects, etc.
Taken from the Official English Rulebook: ...However, for Monsters that are Level 5 or higher, you must Tribute at least 1 monster you control before the Normal Summon. This is called a Tribute Summon. Monsters that are Level 5 or 6 require 1 Tribute and Monsters that are Level 7 or higher require 2 Tributes. Monsters that are Tributed are sent to the Graveyard and the "Tribute Monster" you are Summoning is played in face-up Attack position or face-down Defense position (a.k.a. a "Set").
You of course cannot tribute the opponent's monster for Enemy Controller's activation cost. However if you use Enemy Controller to take control of one of the opponent's monster, that monster can be tributed for a tribute summon, as you are now its controller.
As long as the card that summoned the token does not mention any restrictions, then yes, token monsters may freely be tributed for a summon. Some do have restrictions set on them, for example, Sheep Tokens from Scapegoat cannot be tributed for a tribute summon, but could be tributed as the cost for a Special Summon.
Yes, this is legal. You have two main phases, one either side of the battle phase, there is no rule that says a monster that attacks can't be tributed, or that attacking stops you summoning. You can attack with a monster, then tribute it for a tribute summon in main phase 2.
No, that's not possible. The tribute summoned monster is placed on the field immediately after the tribute is offered. Nothing can go in between these, let alone a Spell Speed 1 spell card.
No, you do not 'tribute' the Synchro Material for a Synchro Summon. They are sent to the graveyard, not tributed. You can tribute an opponents synchro monster for "Assault Mode Activate!" to summon the assault mode monster from your deck.
No, there's absolutely nothing of the sort. The monster goes to the graveyard, just like any other tributed monster.
If you have a level five or higher monster in your hand, you can tribute one or more monster(s) on your side of the field to play it. If a card's cost/flaw (ex.mystic wolk:tribute one monster. Gain life points equal to the original attack of the tributed monster) activates, that tributes as well.
Yes, using a monster's effect in absolutely no way stops it from being tributed later on in the turn.