Yes, this is possible, if you select “free participation” for the gift (select “edit” below the gift). You decide on which gifts “free participation” can apply. Your loved ones will then choose how much they will participate on that gift.

Yes through the screen “manage my gifts”, you can hide the gifts. They will no longer appear in your list. You make them reappear whenever you want.

You can go to the registry and click on "edit" below the gift and then tick the box "show this gift as already offered”.

Go to your registry and select from the menu (on the left) "Manage Gifts". You'll get the list of gifts. You can make a “drag and drop” and change the order of the gifts in your list. Don't forget to save these changes.