Secondary Ledger Vs Primary Ledger Period Closing - Urgent Please help

Hi,

We have primary ledger in normal calendar and secondary ledger in 4/4/5 calendar.

1. Can we close secondary ledger period before closing primary ledger period ? The conversion level is subledger.

2. Will closing the secondary ledger first have impact on transactions posting in primary ledger, as the period in primary ledger take long time to close?

3. How can we avoid back dated transaction for a particular product line where as for others it is allowed by the business?

Any notes or documents about period closing in secondary and primary ledger.

Please help

Thanks

mythson