Explanation:

First statement is incorrect. In Berubari Union (1960) case, Supreme Court had held that the Preamble is not a part of the Constitution. But in Kesavananda Bharati (1973) case it was urged that the Preamble is a part of the constitution and can be amended.

Preamble can be amended, subject to the condition that no amendment is done to the ‘basic features’.
In other words, the Court held that the basic elements or the fundamental features of the Constitution as contained in the Preamble cannot be altered by an amendment under Article 368.
The Preamble has been amended only once so far, in 1976, by the 42nd Constitutional Amendment Act, which has added three new words— Socialist, Secular and Integrity—to the Preamble. This amendment was held to be valid.

Second statement is also incorrect. The preamble was adopted by the Constituent Assembly after the Draft Constitution had been approved.
The basic idea behind it was the preamble should be in conformity with the provisions of the constitution and express in a few words the philosophy of the constitution. It may be recalled that after the transfer of power, the constituent Assembly became sovereign, which is reflected in the use of words “give to ourselves this constitution” in the preamble. It also implied that the preamble emanated from the people of India and sovereignty lies with them.
Chief Jusitce Subba Rao in Golak Nath v. State of Punjab had held that “The preamble to an Act sets out the main objectives which the legislation is intended to achieve”.