the best xyz is the number 39 starter deck
Like Fusion and Synchro monsters, it will return to the Extra Deck. Any attached XYZ material will be placed in the graveyard.
The two terms are mutually exclusive, they are either yellow-bordered Normal monsters or black-bordered XYZ monsters, there is no such thing as a 'Normal XYZ' monster.
No, token monsters cannot be used as material for an XYZ summon.
They are considered effect monsters if they have the /Effect designation in their text box.
There are no Lv3 XYZ monsters because XYZ monsters have a Rank and not a Level, and to all intents they are considered level-less. The Rank 3 XYZ monsters are; - Constellar Hades, - Chronomaly Crystal Chrononaut, - Black Ray Lancer, - Brotherhood of the Fire Fist - Lion Emperor, - Grenosaurus, - Giant Soldier of Steel.
Normal Monsters Effect Monsters Fusion Monsters Ritual Monsters Synchro Monsters XYZ Monsters Spell Cards Trap Cards
Yes of course. They're monsters with levels, just like normal and effect monsters.
There is no "best" deck.
The Rise of the Dragon Lord structure deck would be best (and so far the only) choice.
If you mean Synchro Monsters, they are. The newest ones nowadays are the black Xyz. but before Xyz during the Yu-Gi-Oh 5D's era they were new monsters in your extra deck you summon by sending to the graveyard from your side of the field (most commonly although some require two or specific tuners) a tuner monster and another non tuner monster whose total levels equal the synchro. Hope this helps.
If by 'number monster' you mean cards like some of the XYZ monsters that have 'Number - XX' in their name, then these are just regular monsters when it comes to attacking.
If you're talking about main deck, then you can put any card in as long as it is a valid game-legal Yu-Gi-Oh! card (so no old God Cards)and is not forbidden by the current ban list, nor can you exceed the stated number of a restricted card. You also cannot put Synchro, Fusion or XYZ monsters in your main deck, these go in the Extra Deck, or Side Deck.