What is the difference between "dinsdag zal hij de kleren gebracht hebben" and "dinsdag zal hij de kleren hebben gebracht" ? The first one seems better to me, but I assume they are equally correct?
They are both commonly used and equally correct.
What is the difference between "Op dinsdag..." and "Dinsdag..."?
'op dinsdag' means 'on Tuesday' and 'dinsdag' means 'Tueseday'