invoice approval where there is no PO attached to invoice.

hi folks,

1.for invoice approval in oracle Payable, can we put an invoice for approval to different department manager if there is no PO associated with the invoice?

2. When i tick the invoice approval checkbox in payable options, will this require all the invoices to be approved? or we can make rules? if we can make rules, where we can make?

3- can we make rule that only attachment be approved without considering the invoice lines?

can someone share the set up steps with screenshot for invoice approval workflow.

thanks in advance