sacrafice cards to summon stronger cards
Yes. Face-down monsters can be tributed for tribute summons, card effects, etc.
Yes, the tokens can be tributed. You can't use them for a Tribute or Special Summon in the turn you activated Stray Lambs, but you can that in later turns, but can tribute them for effects like Enemy Controller Straight away.
No, it requires a Tribute. Unless stated otherwise, like on cards such as Soul Exchange, a tribute must be something you control. You cannot tribute an opponent's monster as a cost for your own effects or summons.
If you mean without tribute, then not under normal circumstances. You can tribute summon it by tributing two monsters, or use various effects to lessen the tribute requirement (Kaiser Seahorse) or special summon it.
Sheep Tokens created by Scapegoat cannot be used as tributes for Tribute Summons. They can be tributed to activate effects like Enemy Controller, or for the Special Summon of monsters like D-Hero Plasma, as this is not a 'tribute summon'.
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).
You can tribute a monster when an effect instructs you to, or you need to do so as a cost. So you can tribute a monster for a tribute summon only in your own main phases, when there is no chain in progress. You can however tribute a monster for one of Enemy Controller's effects at Spell Speed 2, in either player's turn, in any phase.
Yes, you can tribute monsters for card effects and Tribute Summon the same turn you summon a monster. However, you cannot Normal Summon a monster and Tribute Summon on the same turn because you can only Normal Summon once per turn. Cards such as Double Summon and Ultimate Offering will let you do that.
Yes. If the tribute is for a Tribute Summon, then you can't attack with any monster again afterwards, since this Summon will occur in Main Phase 2. If the tribute is for a card effect and resolves during the Battle Phase, then you can attack again with another monster, since it would still be the Battle Phase.
In the Yu-Gi-Oh! anime, characters often do not play by the official rules or card effects. It wasn't until the second season that characters performed Tribute Summons.
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.
Well just make a game and but either tribute to (User) tribute for (user) or (users) tribute