Is the Salutation (Taslim) in prayer exclusively for those beside the worshipper, and what about those behind him? And why do many people not complete the Salutation with "wa Barakatuh" to attain thirty rewards, or is this Salutation exclusively for the angels?

We have previously clarified what the worshiper should intend with the first and second salutations, and that the intention of the salutation does not specifically apply to those on the right and left for the congregant. As for the wordings of the salutation, the wording with the addition of "wa barakatuhu" (and His blessings) has been reported in the Sunnah (definition). However, many scholars did not deem it desirable in prayer because most hadiths are to the contrary. Therefore, there should be no denunciation of whoever performs it or omits it, as the matter is broad. As for attaining thirty merits by adding "wa barakatuhu," this applies to salutations outside of prayer, as it is authentically reported in the hadith (definition) from Imran ibn Husayn that greeting with "Assalamu alaykum wa rahmatullahi wa barakatuhu" (Peace be upon you, and the mercy of Allah, and His blessings) is rewarded with thirty good deeds. Al-Hafiz mentioned in Al-Fath that the salutation concludes with "al-barakah" (blessings).