Has anyone tried this? I'm thinking I would like to add crushed pineapple to a cake. Any special tips for how much to add (I usually use box mixes)? Also, will it all sink to the bottom as it bakes? TIA

Take a look at these...
http://cakecentral.com/recipes/category/pineapple-cakes .
If they give you ideas, please feel free to ask about a particular one.