got the collarless shirt in L, I think it's perfect. cav I think you're usually a small? so if you want it to look nice and oversized do M, tts for a just slightly relaxed but fitted look.
I think the shawl blazer is awesome but I could see how someone with less than ideal proportions could find it less flattering. It's a little more advanced, it is a round shape with round details so it's not going to make you look taller or skinnier.