The New Pledge form asks for a total amount of the pledge. I'm working from a spreadsheet where the installment is specified but not a total amount. What is the best way to enter this?
The "recurring payments" approach will only work if you have a CiviCRM payment processor extension that supports it. Other than iATS and CiviSEPA I'm not sure other extensions support ACH/EFT - though I'm not familiar with the non-US processor extensions.
You can also check out the Direct Credit and Direct Debit wiki page.