Advice on edible structural icing and chocolate skulls?

Last year we made sugar skulls for day of the dead. It was a lot of fun but ended in a lot of leftover icing that didn’t taste good.

This year, we’re going to do a group sugar skull thing so we don’t have as much waste afterwards. But I still want to do something with my molds at home.

I was thinking about pouring chocolate into them to make chocolate skulls that I could decorate before devouring. So I have three questions really, any advice you can give on any of them would be appreciated:

1) I’m not a fan of giant chunks of solid chocolate. So to make the walls of the skull thinner, I was thinking of putting something in the middle to create a crater. I’m just not sure what would work? Balloon? Ball? Pear?

2) I kind of want to put a filling in that hole in the center of the skulls. I’m not sure what though. Whole strawberries? Some kind of creamy filling? Peanut butter? Suggestions and recipes for creamy goodness would be nice.

3) The structural icing. I need something that can hold the two halves of the chocolate skull, acting like gingerbread house glue. I also need it to be tasty as we may be decorating the skulls with it too. I never ate gingerbread houses when I was little, so I don’t know of any tasty recipes. I just know that my skull forsting recipes was not tasty and could have broken my jaw if I tried to eat it.

Sorry for all the questions. I’m being indecisive and spending too much time on the internet looking at recipes I’m not sure about.