Under IAS 23, the disclosure requirements include presenting information about the amount of borrowing costs capitalized and expensed during the period. Therefore, the correct answers to your question are:
The amount of borrowing costs expensed during the period. A description of the borrowing costs eligible for capitalization.
The capitalization rate used to determine the amount of borrowing costs eligible for capitalization is not a disclosure requirement under IAS 23, as this rate is an accounting policy matter rather than a disclosure item. However, the policy regarding the recognition of borrowing costs, including the capitalization rate, should be disclosed according to IAS 23. The date capitalization of borrowing costs began is also not a specific disclosure requirement under IAS 23, but the policy on when capitalization starts would typically be disclosed as part of the entity's accounting policies.