As developer you don't have "cash on Steam account". Valve just do automatic payouts to a bank with a delay around ~1 month. As for refunds AFAIK if you have

As developer you don't have "cash on Steam account". Valve just do automatic payouts to a bank with a delay around ~1 month. As for refunds AFAIK if you have bunch of refunds later they will just be substracted from future sales. But games I worked on didnt have refund spikes so no clue how Valve handle situations with mass refunds.