1. Even though one generally is permitted to eat produce in the manner of "Achilas Arai" without separating Ma'aser, one is forbidden from doing so on Shabbos.
2. There is a dispute about whether one may drink water before hearing or reciting Havdalah.
3. One who does not recite Havdalah on Motza'i Shabbos may recite it on Sunday, Monday, or Tuesday.
4. The Gemara says that the honor of Shabbos day is more important than the honor of Shabbos night.
5. Even though one recites Havdalah during his Shemoneh Esreh, he must also recite Havdalah over wine.
A BIT MORE
1. This is because Shabbos establishes any act of eating done on the day as an "Achilas Keva."
2. In the Beis Midrash of Rav Ashi, this was permitted. Rav Huna prohibited it and said that drinking water before Havdalah is dangerous.
3. One who does not recite Kidush on Friday night may do so anytime during Shabbos day.
4. Therefore, if one has a special food with which to honor the Shabbos, it should be served on Shabbos day.
5. He also must taste the wine that he uses for Havdalah.