Freezing breast milk

I have a 2 week old and I'm wanting to pump & freeze breast milk (not yet before anyone starts with 'it's too early' bla bla) can anyone answer these questions please - there's a few lol - I've got breast milk freezer storage bags, do I refrigerate first? Or put straight in the freezer? How long does it last? How do I defrost? With my first daughter (3.5 years ago) I put expressed milk in the refrigerator and it looked like it had curdled .. Is that supposed to happen or was my fridge broken? Lol thanks in advance anyone!