Is there any way I can edit an existing report to be able to see a list of customers with their respective credit limits, account balance and credit status on the one line per customer? This would be useful
xTuple is incredibly customisable. With the Report Maintenance tool inside xTuple you could add those fields to the Customers report, or design a completely new report and add that report as a separate menu option. The fields you are looking for are for the most part easily accessible directly from the customer record with the Account Balance having to be determined from a function.
By Report Maintenance Tool do you mean : System - Design - Reports
Yes, that is what I meant.