Does reciting Surat Taha after Fajr prayer suffice for the day's sustenance, and does reciting Surat Adh-Dhariyat every day benefit sustenance, and does writing Surat Al-Isra with saffron, dissolving it in water, and drinking the water benefit a child who has difficulty speaking?

There is no basis for what was mentioned about Surahs Taha, Adh-Dhariyat, and Al-Isra' in attracting sustenance. The ways to expand sustenance include: fearing Allah (taqwa (definition)), relying upon Him, being diligent in prayer, seeking forgiveness, maintaining kinship ties, giving abundant charity, performing Hajj and 'Umrah (definition) consecutively, and making frequent supplications.