When you select Purchase from the Accounts summary screen the Purchase browse screen will normally be shown.
You can see which suppliers are due to be paid, as the default filter is Due purchases only. You can change to a later date or select all Owing or Paid.
You can go into Accounts / Quick report / Creditors at a date, this will list the individual transactions that were owing at the date set. This is also grouped by supplier.
You can produce a current Aged Debt report in Reports which gives you good ageing details but only shows for the current date (Make sure Paid = No is set in the Criteria otherwise the figures will not be correct).
You can also produce a Creditors control from Accounts / Quick report / Creditors Control. This lists the opening balance, transactions and payments in the period and a closing balance. If there is ever a difference this will normally be because the payment date is dated before the invoice date.