Yes, it does have to be in your hand.
Monster cards: These cards are mainly colored yellow (or somewhat dirty yellow for me) for normal Monsters, Blue for Ritual Monsters and Violet for Fusion monsters. Each has a Name, Level (stars), Picture, Description or Effect, Attack points and Defense points, Attributes and Type. in main rule, you can summon or set monster with level 1-4 without tributes to the field. that is called Normal Summon. You need to sacrifice one Monster to summon a level 5-6 monster and two for level 7 and up. That is called Tribute Summon. Ritual monsters cannot be summoned this way. They require a specific card or cards in order to be summoned. That is what you call Ritual Summon. Fusion Monsters needs specific monsters in order to be summoned not to mention almost all of them needs the Polymerization card. That is what you call Fusion Summon. Putting a monster in face down defense position is called Set. some monsters activate their effect when they are in Set position. if you want to know more about it type "What are the Effects of Yugioh Monster Cards?" Magic or Spell Cards: Colored Green, these cards varies effect per card name. Each has a Name, Icon type (which can be an icon for Equipment, Normal, Continuous, Ritual, Field and Quick Spell), Picture, and effect. if you want to know more about it type "what are the difference in the Icons of Yugioh Magic Cards?" Trap Cards: are colored Maroon. Somewhat similar in Magic or Spell Cards except that it is faster in effect that most Magic or Spell cards. they also has similar part except for the icon which can be a Normal, Counter, or Continuous. if you want to know more about it, type " what are the difference in the Icons of Yugioh Trap Cards?" If you wanna go back, just type "Is yugioh a card game?"
A special summon is any summon that doesn't count as a normal summon, so you can special summon as many monsters as you wish per turn. But someone can't just special summon a monster by themselves. In order to special summon a monster, there must be a card that lets you do so. For example, the card Call of the Haunted lets you special summon a monster from your graveyard. Or, a monster that lets you special summon it in some way is a special summon. Most monsters that let you special summon it have you need to have destroy or remove from play cards. For example, a monster that needs you to remove from play cards is Dark Necrofear. Dark Necrofear can only be special summoned by removing three Fiend-type monsters from your graveyard. Or, there are monsters that can be special summoned when a condition is met. For example, Tragoedia can be special summoned when you take damage. Or, there are monsters that let you special summon monsters from your deck. An example is UFO Turtle. UFO Turtle can special summon any FIRE-attribute monster from your deck with 1500 ATK or less when it is destroyed by battle. Also, Fusion Summoning, Ritual Summoning, and Synchro Summoning all count as Special Summoning.
Answer taken from the Official English Rulebook: When you have a Ritual Spell Card, along with the matching Ritual Monster Card, in your hand, along with the required Tribute (as listed on the Ritual Spell Card), you can activate the Ritual Spell Card, placing it in the Spell & Trap Card Zone. If the activation of the Ritual Spell Card is successful, Tribute monsters by sending them from your hand or the field to the Graveyard. The Ritual Spell Card will list the required amount to Tribute. After sending the Tributed Monsters to the Graveyard, play the Ritual Monster Card onto the field in either face-up Attack or Defense Position. Finally, place the Ritual Spell Card in the Graveyard. In your case, "Black Luster Ritual" would be activated once you have "Black Luster Solider" in your hand. Now you pick monsters (other than "Black Luster Solider", of course) that are on your field or hand and send them to the Graveyard. The stars of the monsters that you select must total up to 8 or more in order to Ritual Summon the 8-star "Black Luster Solider". Then you Summon "Black Luster Solider" from your hand; this is treated as a Special Summon so you can Normal Summon or Set another monster that same turn.
You only need 2, like any other tribute monster that's level is 7+
Synchro Monsters can be summoned from the Extra Deck (formally known as the Fusion Deck) by a Synchro Summon.A Synchro Summon can only be performed with one Tuner Monster and one or more face-up, non-Tuner monsters you control (with XX-Saber Gottoms as the exception, who can be Synchro Summoned with more than one Tuner Monster). You can tell if a monster is a Tuner by looking at the card type and seeing "/Tuner" next to it. For example, you can tell Junk Synchron is a Tuner since its card text shows "[Warrior/Tuner]".In order to Synchro Summon a Synchro Monster, the Levels of the monsters used must equal the Level of the Synchro Monster. For example, Gaia Knight - the Force of the Earth is a Level 6 Synchro Monster. That means Junk Synchron, a Level 3 monster, would need a monster(s) whose Level equals 3 to Synchro Summon that Synchro Monster (or any other Level 6 Synchro Monster for that matter). Once you have met the requirements, you can send the monsters from the field to the Graveyard and Synchro Summon the Synchro Monster (this still counts as a Special Summon).Just remember, unlike Gaia Knight - the Force of the Earth, who doesn't have any specific requirements besides a combined Level of 6, some other Synchro Monsters do. Some require specific Types, Attributes, Archetypes or monsters to be used.
No... a level 4 monster can be summoned without a tribute monster, but a level 5 and 6 needs 1 tribute monster and level 7 and so on needs 2 tribute monsters.
Yes, the Normal Summon can trigger both Tin Goldfish and Kagetokage. Their effects would form a chain with each other, you'd choose the order since both are the same kind of trigger, your Optional Triggers.
No, cards like 'Polymerization', 'Future Fusion', and 'Fusion Gate' cannot be used to summon any of the XYZ Fusion Monsters. These Fusion Monsters cannot be Fusion Summoned and requires you to banish the monsters listed on the Fusion Monster from your side of the field in order to Special Summon them.
Yes. Since you can't special summon, you can't even begin to initiate any kind of special summon. That means assuming a special summon card has a cost of tributing/banishing one monster, you could not use Kristya as that cost. Even if the summon does not use the chain, it is still not possible to tribute/banish Kristya. So the opponent could not tribute your Kristya for his Lava Golem.
"I feared that my professor would summon me to his office in order to criticize my project."
Ritual is the things a Hindu must do, in order to qualify as Hindu. Ritual represent Ancient civilization & their thoughts.
No, you do not use Cobalion, Terrakion and Virizion in order to summon Keldeo.