Shabbat is what it is because God imbued it with its special qualities (Genesis ch.2). This connects with the Jewish people because God commanded them to keep the Shabbat (Exodus ch.20 and many other verses).
God gave us the gift of the Shabbat because He knows that we need "time out;" time to regroup, to relax, to hear the Torah being read and to discuss it, to reconnect with God, with our communities, and with and our family, and to be without the constant background noise of cell-phones etc., etc.
They prepare their children for Shabbat and light the Shabbat candles.
"Shabbat Shalom!"
They're called Shabbat candles (Neirot Shabbat in Hebrew).
After Shabbat, there is the Havdalah service.
Shabbat Shabbatot
Shabbat comes from the Hebrew word for sit/rest. Shabbat is the day of rest.
Shabbat shalom is a Jewish greeting which we say during the day of Shabbat. See also:More about the Jewish Shabbat
Shabbat Shalom (שבת שלום).Note: This means 'A peaceful shabbat'. The phrase "happy shabbat" is not a phrase that is traditionally used.
There is no issue with swimming during Shabbat, however, you wouldn't be able to shower after swimming until Shabbat ends. (Assuming you wish to be Shabbat observant.)
Judaism.See also:More about Shabbat
There is no reason to not allow Shabbat.
They say Shabbat blessings for their children.