Masturbation is stimulating the genitalia for the sake of ejaculation. This is prohibited. But if a person was unaware of it being prohibited, then God may overlook this. If ejaculation occurs, then the person enters the state of janabah, and he is required to undertake the ghusl. If he did not do so, the prayers after that will be invalid. If he undertakes ghusl for another reason, e.g. the ghusl of Friday, the state of janabah ends and the prayers after this ghusl are valid until he enters the state of janabah through masturbation again. He will need to repeat those prayers that were invalid because of the failure to do ghusl.
It is obligatory to mention the name of Almighty Allah on the sacrifice during the actual slaughtering and it is not sufficient to mention the names of the Infallible Imams. If the slaughterer did not mention the name of Almighty Allah during the slaughtering process, it is prohibited to consume the animal. Yes, it is recommended to recite the Salawat on the Prophet and his progeny (peace be upon them all) during the slaughtering process.
It is not permissible for the person in the state of janabah to recite the verses of prostration. He may recite the rest of the Quran.
It is permissible but disliked, and it is not amongst the duties of the wife to her husband, i.e. she can refuse to let him if she does not want to.