Friday
The blessings of the Havdalah ceremony mark the end of Shabbat.
At a shabbat service at your home or at a synogauge you may light the shabbat candles and say the shabbat blessings. Also some people follow it with hallah and/or a kiddush.
Only in years where Yom Kippur happens to fall on Shabbat (Saturday). Otherwise, no.
E-Mail BEFORE Shabbat.
Religiously observant Jews would not board a plane if Shabbat were to start while in transit. The issue wouldn't be landing during Shabbat, the issue would be flying during Shabbat.
Yes.
Shabbat (Hebrew for 'Sabbath') begins slightly before sunset on Friday afternoon, and ends after twilight on Saturday night.
We don't "get around" it. We obey the Torah's command. Note that lights may be left on from before the Shabbat; and they may be switched off or on through the use of electric timers which are set before Shabbat. This doesn't constitute "gettting around," since it is completely permissible.
A dvar Torah before Musaf on Shabbat is a way to enhance the spiritual experience of the service by providing insights and reflections on the weekly Torah portion or other Jewish teachings. It helps to connect the congregation to the themes of Shabbat and inspire them to deepen their understanding and connection to the prayers they are about to recite.
Yes, in the morning or afternoon.
They prepare their children for Shabbat and light the Shabbat candles.
Jews do not call the sabbat "Saturday", it is called 'Shabbat'. Shabbat happens to start Friday at sundown and ends Saturday at sundown, the 7th day of the week.