Were there students of knowledge, scholars, andخطباء (preachers/orators) during the Prophetic era, and what was the intended knowledge at that time: the Quran, Fiqh (jurisprudence), the Sirah (Prophet's biography), or something else?

All of the Companions were seekers of knowledge, because asking the Prophet, peace and blessings be upon him, was considered seeking knowledge.

There is no classification of the Companions as "students of knowledge" in the later, specialized sense.

As for the scholars among the Companions, they were many, headed by the Rightly Guided Caliphs, and fatwas were narrated from more than a hundred of them.

The seven Companions who issued the most fatwas were: Aisha, Umar, Ibn Umar, Ali, Ibn Abbas, Ibn Mas'ud, and Zayd ibn Thabit.

The knowledge that the Companions engaged in was the precise understanding of the words and meanings of the Qur'an and Sunnah.

Some Companions excelled in specific fields, such as Ubayy ibn Ka'b in recitation, Ibn Abbas in exegesis, Abu Hurairah in memorizing hadith, Zayd ibn Thabit in inheritance laws, and Mu'adh ibn Jabal in lawful and unlawful matters.

The Messenger of Allah, peace and blessings be upon him, said: "The most knowledgeable of my Ummah concerning what is lawful and unlawful is Mu'adh ibn Jabal, the most knowledgeable concerning inheritance laws is Zayd ibn Thabit, and the best reciter is Ubayy ibn Ka'b."