Hi saurabh chugh,
A. Yes you will be due private residence relief for the period you lived in it.
B. As sold in the 22/23 tax year, it needs to be reported in that years ta return and the due date for the return and any liability is 31/1/24
C. If the purchase payments were all in the same tax year, you can use any of the export rates within that year. for the sale it will be the date of the sale.
Details of exhange rates are here:
Exchange rates from HMRC in CSV and XML format
Thank you.