Question: May a person under the age of 40 publish a sefer on halachah?

Short Answer: While there was a takanah in Prague a few hundred years ago not to publish, there are many leniencies to allow a talmid chacham to publish a sefer halachah nowadays.

Question: If you forget to perform b’dikas chametz and you remember on Chol HaMoed, should you wait until the night to perform b’dikas chametz or do it right away?

Short Answer: It is a machlokes when the b’dikah should be done, but most poskim say it should be performed as soon as you remember. There is also a dispute whether a brachah is recited on this b’dikah.

Question: Should a person residing in Yerushalayim go to Tel Aviv (or the like) to hear Megillah a day early, on the 14th of Adar?

Short Answer: Rav Yosef Dov Soloveitchik zt”l cites a machlokes Rambam and Ramban whether the 14th or 15th day of Adar is the main day of Purim. This author suggests that if the 14th day is the main day, perhaps it is preferable for someone in Yerushalayim to hear the Megillah on 14 Adar.

Question: May a shaliach eat before doing b’dikas chametz in his friend’s house?

Short Answer: There is a dispute whether a shaliach may eat before performing someone else’s mitzvah for him. Practically, it is probably better for the shaliach to refrain from eating beforehand unless he must.