fungo circles
The dirt circles are called fungo circles and are used by the coach to hit flyball practice to the fielders before the games.
Ritual monsters, and the rituals for them are in your regular deck.
A teammate cannot use an extra deck tag during dueling. Each player holds their own extra deck and it is not possible to use another teammates for play.
No, it does not.The only possible overlap, is if an effect tries to put a Synchro or Fusion monster in hand or main deck, these are returned to the Extra Deck instead, as a specific replacement effect.
No. If a card says to 'search your Deck', or 'send a card from the top of your Deck', this means your main deck. If something tries to return a Fusion monster 'to deck' though, that will put it back in your Extra Deck. That doesn't mean Extra Deck is the considered the same thing, that's just where Fusions and Synchros go when something tries to put them back in Deck.
You can have up to 15 synchro's or fussion monsters total in your extra deck.
No, it doesn't. The 40-60 limitation is for your main deck only.
the 2 circles by home plate on a baseball field are called the on-deck circles and they are for the next player up to bat to warm up before going to home plate
No, how would that even work? If you don't have an Extra Deck, then you don't have the Five-Headed Dragon card available to you.
Synchro Monsters are placed in the Extra Deck along with the Fusion Monsters at the beginning of a Duel.
The Extra Deck is just the new name for the Fusion Deck. It contains all your Fusion and Synchro Monsters. A Side Deck is a group of 15 cards you can swap out in a Match Duel (a best two-out-of-three duel). How it works is after the first duel (or after the second duel if the score is tied), you can swap one or more cards out of your regular deck for the same number of cards from your Side Deck. This helps by adding cards on the spot to counter your opponent's deck.