Is the opening Takbir required for the prostration of thankfulness (sujud al-shukr)? And is it obligatory to supplicate and thank Allah during the prostration of thankfulness to achieve its meaning?

The prostration of thankfulness (sujud ash-shukr) is legislated outside of prayer. Its form is similar to that of the prostration of recitation (sujud at-tilawah). It involves a takbir (saying "Allahu Akbar") when descending for prostration and another when rising from it, without raising the hands. It is legislated to perform tasbih (glorification of Allah), supplication (du'a), and express gratitude to Allah therein. It is recommended to say "Subhana Rabbi al-A'la" (Glory be to my Lord, the Most High) and what was reported from the Prophet, peace and blessings be upon him: "My face has prostrated to the One Who created it and fashioned it, and split its hearing and sight, by His power and strength."