How to offer Istikharah and Salah for need

A: The manner of performing Salat-ul-Istikharah was mentioned in the Hadith of the Prophet (peace be upon him) that was reported by Al-Bukhari, Abu Dawud, Al-Tirmidhy, Al-Nasa'y, and Ibn Majah on the authority of Jabir ibn `Abdullah (may Allah be pleased with him). He said, The Messenger of Allah (peace be upon him) used to teach us the Istikharah for each and every matter as he used to teach us the Surahs from the Qur'an. He used to say, 'If any of you intends to do something, he should offer a Salah of two Rak`ahs other than the obligatory Salah, and then say: Allahumma inni astakhiruka bi `ilmika, Wa astaqdiruka bi-qudratika, Wa as’aluka min fadlika al-`azim Fa-innaka taqdiru Wala aqdiru, Wa ta`lamu Wala a`lamu, Wa anta `allamu l-ghuyub. Allahumma, in kunta ta`lam anna hadha-l-amra Khairun li fi dini wa ma`ashi wa`aqibati amri (or `ajili amri wa'ajilihi) Faqdirhu li wa yas-sirhu li thumma barik li Fihi, Wa in kunta ta`lamu anna hadha-lamra shar-run li fi dini wa ma`ashi wa`aqibati amri (or `ajili amri wa'ajilihi) Fasrifhu `anni was-rifni `anhu. Waqdir li al-khaira haithu kana Thumma irdini bihi. (O Allah! I ask guidance from Your knowledge, and Power from Your Might and I ask for Your great blessings. You are capable and I am not. You know and I do not and You know the unseen. O Allah! If You know that this matter is good for my religion and my subsistence and in my Hereafter - (or said: If it is better for my present and later needs), then You ordain it for me and make it easy for me to get, and then bless me with it. And if You know that this matter is harmful to me in my religion and subsistence and in the Hereafter - (or said: If it is worse for my present and later needs), then keep it away from me and keep me away from it. And ordain for me whatever is good for me, and make me satisfied with it). The Prophet (peace be upon him) added that then the person should name his need." (Part No. 8; Page No. 161) One should begin his recitation in this Salah by Al-Fatihah and then a Surah or part of a Surah of the Qur'an.As for what is called Salah for need, it was reported in a Hadith Munkar (rejected Hadith reported by a weak narrator whose narration conflicts with an authentic Hadith) and weak ones. Therefore, these Hadiths can not be used as evidence and we cannot establish acts of worship upon weak Hadiths.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.