Is This Permitted?

If somebody gets plastic surgery, do the implants ever count as Chatzitzah. For example for a woman who gets breast implants, will that be a Chatzitzah for the mikveh? Sources for the Halacha/responsa regardinf this question please

Does somebody fulfill the Mitzvah of Chinuch if they get a rabbi or day school at a synagogue to teach their children Jewish ritual/halacha? Or is it necessary for them to teach children themselves without outside help

Can I take a tune of a Christian song and change the lyrics to make it Jewish? Is it permitted being that it is a mitzvah to turn a church into a synagogue?

If one has to take a job that involves doing something that could lead to deaths (e.g. manufacturing bombs for a country not yet at war, but talking about it) in order to earn enough money to save your brother's life, is it ethically acceptable to take this work? (Situation in a novel I'm writing.)

Shalom aleichem Rabbi Lauffer. Thank you for answering my last question. Would it be permitted to brush one’s teeth with toothpaste after sunrise but before davening shacharis? Thanks.

Is it permitted to trim tzitzit strings on tallit katan if they are very long (e.g. knee length) and get in the way? If so, by how much?

I know you people have a commandment not to commit murder. And you are not supposed to violate it even to save a life. Then what permits killing in self defense?

If someone were to theoretically take a nazarite vow, could they be allowed to trim their moustache if it made simple tasks such as eating food less troublesome? For the vow it is written to not cut a hair on the head so would this include facial hair, eyebrows, and even nose hairs?

My neighbor says he likes my sukkah so much, he has offered to trade his with me for mine. He showed me his and I actually like his better than mine because it is more spacious. He likes the material mine is made of. I am not badly attached to my sukkah. I got it several years ago from someone who was giving it away. I actually like this trade. Does Halacha permit this? One of my concerns is that either of us could be violating the tenth commandment by coveting a neighbor’s property, even if we both agree to this trade.