Assuming the monster doesn't have any special text which explains how to summon it, then a 10 star monster just requires two tributes, because Lv7+ monsters need two. The Earthbound Immortals and Andro Sphinx/Sphinx Teleia are Lv10 monsters that are tribute summoned as normal with just two tributes.
2
First you need to beat the game. Then you can either talk to Crow who's south of the satellite then he will tell you about a shadow where you dueled kalin. Beat that shadow in a turbo duel then talk to crow again to unlock a pack containing a few earthbound immortals. Also after you beat that shadow you can then go to where you dueled Roman. There's another shadow there to beat for another earthbound immortal pack, but you will need to talk to crow after you beat them. Also you can talk to the MC in the fortune cup and he will tell you about another shadow in the duel stadium. Beat that then talk to the MC again to unlock the pack for some earthbound immortals.
As per the basic rulebook, you need two tributes for monsters of Lv7+. Some high level monsters have rules text to say they require three tributes, but these are exceptions. In the case of monsters like Yubel (Lv10) they still only require two tributes.
You need to tribute one monster for the tribute summon of a Lv5 or 6 monster, and two tributes for any that are Lv7 or higher, even Lv10 ones like Yubel. Additionally, some monsters require three tributes (Obelisk the Tormentor, for example), but that is stated on the card, and it not related to the level.
Assuming the monster doesn't have any special text which explains how to summon it, then a 10 star monster just requires two tributes, because Lv7+ monsters need two. The Earthbound Immortals and Andro Sphinx/Sphinx Teleia are Lv10 monsters that are tribute summoned as normal with just two tributes.
2
First you need to beat the game. Then you can either talk to Crow who's south of the satellite then he will tell you about a shadow where you dueled kalin. Beat that shadow in a turbo duel then talk to crow again to unlock a pack containing a few earthbound immortals. Also after you beat that shadow you can then go to where you dueled Roman. There's another shadow there to beat for another earthbound immortal pack, but you will need to talk to crow after you beat them. Also you can talk to the MC in the fortune cup and he will tell you about another shadow in the duel stadium. Beat that then talk to the MC again to unlock the pack for some earthbound immortals.
Monsters of Lv5 or 6 need one tribute, and monsters of Lv7+ need two. So even monsters like Yubel (Lv10) only requires two tributes. Some high level monsters do require three tributes. These will always say so on their card.
Immortal Technique don't need sex.
As per the basic rulebook, you need two tributes for monsters of Lv7+. Some high level monsters have rules text to say they require three tributes, but these are exceptions. In the case of monsters like Yubel (Lv10) they still only require two tributes.
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, but you need to floss after meals.
The electric field that would throw them back on the roof is what prevents tributes from jumping. This is probably placed so that none of the tributes can commit suicide or escape before, or during, the games. The Capitol doesn't want tributes to die before the games so they can watch them die for entertainment, or need to get another tribute last minute.
You need to tribute one monster for the tribute summon of a Lv5 or 6 monster, and two tributes for any that are Lv7 or higher, even Lv10 ones like Yubel. Additionally, some monsters require three tributes (Obelisk the Tormentor, for example), but that is stated on the card, and it not related to the level.
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.
In the Yu-Gi-Oh rule book it states that an 8 star monster only needs 2 tributes.