Expense Report Receipt Attachments

We are getting ready to implement allowing users to attach their receipts to their expense reports. We currently use ImageNow to store the receipts, but want to convert to the delivered Attachment functionality.
We are wondering how other companies manage this. Do you allow attachments at the line and/or header level. How does this impact the approvers/auditors when they need to view the receipts? Do you limit the size and/or type of attachments? Do you save the attachments to a file server or database?
Any advice is welcome!
Thanks,
Alicia

@Alicia Kinsey

We attach at the header level. The approvers can review the receipts at once instead of clicking on each line item and reviewing. We do limit to 10MB. We are configured to save the receipts on the file server.