Can you keep presents/cousins from Eternal mode?

[SuperPhillip]

Also, is there a way to see what levels you've collected presents and cousins in?

[The Pants Party]

You do keep them from Eternal, yes.

And to see what you've collected, head to a level in the Princedom and look at the top left if I remember correctly, it shows what you have or a "?" if you don't have it.

[DarthJoshua]

That's correct. Just walk up to a level and press which ever button it is to go into that level. Then just look in the top left corner and it will show you which cousins and presents you've picked up and the number left in the level.