The custom of the Arizal (Rav Yitzhak Luria of Safed, 1534-1572) was to hide ten pieces of bread that were smaller than a Ke’zayit throughout the home before Bedikat Hametz. This custom was undoubtedly based upon deep Kabbalistic reasons, but nowadays, it might be mandatory for Halachic reasons, as well. We recite the Beracha of "Al Bi’ur Hametz" before beginning the search because we assume that we will find some Hametz, and thus the search is part of the process of eliminating Hametz from the home. Nowadays, however, the wives thoroughly clean the home well in advance of Bedikat Hametz, going through every area of the home and eliminating Hametz. The real Bedika, therefore, was done before the formal search which we conduct on the night of Ereb Pesah. Therefore, if one does not spread some pieces of bread around the home before the Bedika, odds are that he will not find any Hametz, and his Beracha might then be considered a Beracha Le’batala (Beracha recited in vain). Our situation is thus much different than the situation years ago, when the main search for Hametz was the formal Bedika, and it could be assumed that some Hametz would be discovered over the course of the search. For this reason, Rav Yosef Shalom Elyashiv (1910-2012) ruled that it is obligatory to put out ten pieces of bread before Bedikat Hametz.
This distinction between the situation today and the situation in years past can also help explain the common practice to conduct a brief, casual search on the night of Bedikat Hametz, rather than thoroughly searching through the entire house. As noted by the Hida (Rav Haim Yosef David Azulai, 1724-1807) in Mahazik Beracha, those who do not conduct a thorough search rely on the fact that the home had already been cleaned well before the night of Bedikat Hametz, and care was taken to ensure that no Hametz was brought into the home. It is therefore acceptable to make a cursory search to fulfill the Misva. Likewise, the car is usually cleaned before the night of Bedikat Hametz, and people just briefly check the car once more superficially, without thoroughly searching, to fulfill the Misva. Of course, it is proper to spend time searching, and there is educational value to searching for Hametz together with one’s children, but there is room to justify the common practice to search perfunctorily, since the real "Bedika" had already been done.
It is not advisable when distributing the ten pieces of bread to wrap them in aluminum foil, for the simple reason that aluminum foil is not flammable. If the bread is wrapped in foil, then it will have to be taken out of the foil the next morning for the burning, which could cause crumbs to fall. It is far preferable to wrap the pieces of bread in newspaper and close it with a piece of scotch tape, so then it can be easily thrown into the fire and burned the next morning.
If a house, for whatever reason, was not searched for Hametz, may one enter the home over Pesah? An example of such a case is one who owns a summer home that has food in it, and he does not plan on living in the home during Pesah, and so he simply sells the Hametz in the home, without searching for Hametz. If he needs to go into the home to get a suit or a book, for example, may he enter the home on Pesah, or is this forbidden, since there is Hametz in the home?
Rabbi Karp, in his work Hilchot Hag Be’Hag (p. 118), writes that one may enter a home temporarily during Pesah, such as to retrieve something, but one may not live there during Pesah. This applies also to the home of a non-Jew, who obviously has Hametz in the house. One may visit the home temporarily, but one should not live there during Pesah. One may perform a Bedika during Pesah if the home was not searched before Pesah, and may then live there, but if no Bedika is done, one may only enter temporarily. Rabbi Karp adds that if a synagogue was not checked for Hametz it is nevertheless permissible to learn and pray in that synagogue during Pesah.
Summary: There is a well-known custom to place ten pieces of bread throughout the house before Bedikat Hametz, and this custom should be followed, for both Halachic and Kabbalistic reasons. Nowadays, when the house is cleaned over the course of the days and weeks before Pesah, it is acceptable to make a brief search for Bedikat Hametz, though it is proper to spend some time searching with one’s family. If one has a second home with Hametz in it and he sold the Hametz, without searching the home, he may enter the home temporarily during Pesah, but may not live there during Pesah, unless he first conducts a thorough Bedikat Hametz (which may be done on Pesah).
