If refund is made based on the order of appellant authority, then would interest be paid

Yes, interest (at a rate not exceeding 9%) would be computed and paid for the period starting from expiry of 60 days from the date of application consequent to the order till the date of actual refund of tax. It is pertinent to note that the Government vide Notification No. 13/2017 – Central Tax dated June 28,2017, has prescribed the rate of interest @ 9%.

(ICAI FAQ PUBLICATIONS 06-09-2017 INTEREST ON DELAYED REFUNDS: FAQ NO. 31)

Would interest be paid on the amount of refund sanctioned

Yes, in terms of section 56, interest would be paid at a rate not exceeding 6%, if the refund is not sanctioned with 60 days from the receipt of refund application. It is pertinent to note that the Government vide Notification No. 13/2017 – Central Tax dated June 28,2017 has prescribed the rate of interest @ 6%.

(ICAI FAQ PUBLICATIONS 06-09-2017 REFUNDS: FAQ NO. 29)

Is there any other case apart from those covered in Section 54, wherein refund can be claimed under GST

Yes, as per Section 55 of the CGST Act, the Government may, on the
recommendations of the Council, by notification, specify any specialised agency of the United Nations Organisation or any Multilateral Financial Institution and Organisation notified under the United Nations (Privileges and Immunities) Act, 1947, Consulate or Embassy of foreign countries and any other person or class of persons as may be specified in this behalf, who shall, subject to certain conditions and restrictions, be entitled to claim a refund of taxes paid on the notified supplies of goods or services or both received by them.

(ICAI FAQ PUBLICATIONS 06-09-2017 REFUND IN CERTAIN CASES: FAQ NO. 28)

What are the prior procedures for persons making zero rated supplies to claim refund of taxes paid in relation to supply of goods or services under bond or Letter of Undertaking

Any registered person availing the option to make a zero rated supply of goods or services without payment of integrated tax shall furnish a bond or a Letter of Undertaking in FORM GST RFD-11 prior to execution of such supply.

(ICAI FAQ PUBLICATIONS 06-09-2017 REFUNDS: FAQ NO. 24)

What is the procedure for claim and grant of refund of IGST paid on goods exported out of India

FORM RFD-01 is to be filed after:
(a) the person in charge of the conveyance carrying the export goods duly files an export manifest or an export report covering the number and the date of shipping bills or bills of export delivers it under Section 41 of Custom Act 1962; and
(b) the applicant has furnished a valid return in FORM GSTR-3 or FORM GSTR- 3B, as the case may be. Upon the receipt of the information regarding the furnishing of a valid return as mentioned above, the system designated by the Customs shall process the claim for refund and an amount equal to the IGST paid in respect of each shipping bill shall be electronically credited to the bank account of the applicant.

(ICAI FAQ PUBLICATIONS 06-09-2017 REFUNDS: FAQ NO. 23)