For example the system is asking which transactions are debits and which are credits. There are no income/credit or expense/debit fields in the PayPal file."
If your CSV file is both positive and negative numbers combined into one column, just select that column for the Amount field on MAP CSV columns import screen. Since it's an import for the bank account, it will figure out which side is debit and which side is credit when importing to the QBO Banking tab. You should see Money-In on the Received column and Money-Out on the Spent column.
Note: For Bank Account, the debit side is Money-In (Received) and the credit side is Money-Out (Spent).
Hope this helps!