The key principles of federalism in India include:

• Distribution of powers: The Constitution of India clearly outlines the separation of powers between the central government and the state governments. Certain subjects are under the exclusive jurisdiction of the central government, while others fall under the purview of the state governments.
• Supremacy of the Constitution: Both the central government and the state governments derive their powers from the Constitution. They are bound to uphold and protect the Constitution, and any laws that violate its provisions can be declared as unconstitutional by the judiciary.
• Independent judiciary: The judiciary in India acts as an impartial arbiter between the central and state governments. It interprets and enforces the provisions of the Constitution, resolving any disputes that may arise between the different levels of government.
• Residual powers: While certain subjects are clearly enumerated in the Constitution as being under the authority of either the central government or the state governments, residual powers that are not specifically mentioned are vested in the central government.
• Interstate relations: The central government acts as a mediator in resolving inter-state disputes and maintains harmonious relations between different states within the country.

It is important to note that these principles may have variations and interpretations in practice, but they provide the foundation for the federal structure of India. Regarding the Congress party's questions about the Prime Minister's silence over the CAG reports, it is necessary to have more specific information to provide a point-wise answer.