The location where the chainring and cranks touch. Some are through bolts and others are a spider (i.e. Raceface and SRAM). Grease in these locations typically resolves creaks. You can use blue loctite on the bolts too, but sometimes a little dab of grease is all you need.
Dang, that's unlucky! Well, maybe it would help the next person looking or if you get the same wheel. Your bike would have the Line Comp 30 wheels.
Front wheel bearing:
Part # 431759 - 18307 Bearing 18x30x7
Rear wheel bearing:
Part # 432399 - 6903 Bearing 30x17x7mm
Blue threadlocker/loctite would be your best option, just an FYI. I've seen folks use red which isn't a good choice on something that you want to be able to remove without a fight.
Also, check your chainring interface - clean it up and apply grease which often helps!