No. Demeter is the daughter of Kronos and Rhea. She and Zeus are siblings.
Zeus is the brother of Demeter
Demeter is Zeus' older sister
Demeter had one daughter with Zeus: Persephone.
No, Zeus and Hestia never had a child. Hestia was the virgin sister of Zeus. Zeus had children by both his other sisters, Demeter and Hera - only Hera he married.
Persephone's parents are Zeus and Demeter.
Zeus and Demeter were not lovers. Demeter bore a daughter by Zeus named Persephone (Kore), however Zeus married his other sister, Hera. (Note that Zeus mated with many other goddesses and mortals, not just his lover and Demeter)
Demeter and Zeus did not marry, but did have the child Persephone/Kore.
Yes, Demeter and Zeus were lovers. They produced a daughter Persephone.
Zeus has three sisters: Hera (who is also Zeus' wife), Hestia and Demeter.
Demeter's childhood was short lived. When she was a kid she was swallowed by her dad, Kronos. When Zeus poisoned Kronos and she came back up she was a fully grown woman.
Demeter and Hestia were her sisters. She also had three brothers Zeus, Poseidon, and Hades.
There was only one child between Zeus and Demeter, and that was Persephone.