It should be possible to set up a new payee without sending money at that point in time.
During setup the sort code should show the bank and branch to confirm it is correct (Handelsbanken does this) and a modulus check should be performed on the account number to ensure it belongs to the accounts numbers at that branch. Faster payments suffers from not validating recipients at the point of setup so anything Starling can do to mitigate this would be helpful.
References should default to upper case character at the start.
The total amount sent to a payee should list the individual transactions.