General Ledger questions.

1)Invoice approval work flow
2)Invoice validations
3)Invoice accounting
4)Auto invoice in Accounts pay ables
5)Legacy P.O's conversions
6)legacy Invoice's conversions
7)Autoaccounting,autocash rule set
8)How many set of books attach to one legal entity
9)Many set of books attach to one operating unit
10)Expense invoice
11)Recurring Invoice
12)Budget's
13)After permanently closed period. in the same period how to pass transactions.
14)We passed one invoice with 90 days payments term but we paid amount to supplier after 10 days how do in apps a.p
15)What is use of set of books
16)Debit invoice and credit invoice accounting in apps