The Mechaber (444:3) says that, for Shabbos Erev Pesach, one should not cook foods that stick to the pot. Since the pots will not be used anymore on that day, it is prohibited to wash them out. This falls under the category of hachana – preparing for after Shabbos- which is prohibited. There will be no way to get rid of the chometz. The Rema says that if one did cook chometz that is stuck to the pot he may lightly rinse it off in order to get rid of it. It is better to have a non-Jew clean the pots.
The Mishnah Berura says that the minhag is not to cook any chometz for this Shabbos. One should not even cook chometz in a disposable pan. If there is leftover chometz stuck to the pan it may be very difficult to get rid of. One cannot pour it down the toilet and, if there is no eiruv, he can’t throw it into a Reshus Harabim.
No preparations for Pesach can be done on Shabbos. It is preferable to do them before Shabbos, rather than after, so that the seder can start right away. The chairs and anything else needed for reclining should be set up before Shabbos unless that can quickly be done on Motzai Shabbos. If one needs the chairs and tables for Shabbos, he may ask a non-Jew to set it up on Shabbos after he is finished using them. If there is no goy, it may be done by a Jew.
If one will be having his seder at someone else’s house he cannot bring his kara, matzos and kittel there on Shabbos. There is room to be lenient, since one is bringing what he needs for the seder so it could start immediately. The Mechaber (472:1) says that the seder should start right away. He is not bringing it to save time or to save himself from any extra exertion. This is the same reason one may have a goy set up the chairs and tables on Shabbos.
The Chayei Adam and Kitzur Shulchan Aruch are of the opinion that the salt water should not be made on Yom Tov. Therefore one should make the salt water before Shabbos.
One should also not change from his Shabbos clothing to Yom Tov clothing close to shkia. If he is doing so because he is afraid there may be crumbs in his clothing then it is considered a necessity for Shabbos. However, he must change them before chatzos, when the issur chometz starts. Even if he is not worried about chometz, he may change his clothing by chatzos since he is also wearing them for Shabbos.
It is permissible to nap on Shabbos in order to be awake for the seder. However one should not speak out that he is doing so for that reason. As far as going to the mikvah for Yom Tov, some poskim hold that when he goes on Shabbos, he should also have Yom Tov in mind. Reb Shlomo Zalman zt”l holds that one may go on Shabbos for Yom Tov. Most Poskim disagree.1
Prepared by R’ Avrohom Yehoshua Ziskind
1Sources: Mishna Berura, Piskei Teshuvos