1. One is not allowed to start a journey by boat within three days before Shabbos.
2. Rebbi Tzadok describes the custom of Raban Gamliel regarding giving clothes, before Shabbos, to a Nochri launderer.
3. The Gemara explains why Beis Shamai agreed that one may crush olives before Shabbos even though their oil will continue to flow on Shabbos.
4. There is a dispute about whether or not such olive oil (#3) may be used on Shabbos.
5. One is allowed to put something on an open fire immediately before Shabbos only when it is already partially cooked.
A BIT MORE
1. This applies only when he wants to travel for a mundane matter. If the purpose of his trip is to fulfill a Mitzvah, then he may embark within this time.
2. Raban Gamliel would give white clothes to a Nochri launderer only three days before Shabbos, but he would give colored clothes even on Erev Shabbos. This teaches that white clothes are much more difficult to wash.
3. Since having these oils flow by themselves is not a Torah prohibition on Shabbos, Beis Shamai permitted it.
4. The Beraisa forbids it, while Rebbi Elazar and Rebbi Shimon permit it.
5. The Gemara later explains that this amount of cooking is known as "Ma'achal ben Derusai" (either one-third or one-half cooked).