import

Ques:
-Import purchases $10000 (CF value)
-Bill of entry exchange rate - Rs. 45 (20.05.2010)
-assessable value for custom duty calculation (CF value+1.125%insurance+1% landing charges)X Rs. 45
- Exchange rate on actual payment Rs. 47 ($10000),
(4.04.2010) advance payment.

please help me with entry ,,, on following points :-
1. date for purchases ?
2. value for purchases ? assessable value (cif)?
3. whether to book insurance and landing charges separately ? or not?
4. treatment of diff due to exchange rate?

please suggest me any file in relation to accounting entries for import purchases,

thanks in advance