Hi and congrats on a great lens!

Of course it may be personal preference, but in my opinion all three skating shots are more or less underexposed. Instead of using exposure compensation in a venue like this, my suggestion would be to lock the exposure manually - it shouldn't vary too much across the ice. Judging from the EXIF you provided for these shots I'd suggest f/2.8, 1/400 sec and ISO3200 or even brighter (e.g. 1/500-1/640 sec at ISO6400).

Have fun getting to know your new "best friend"!