Hello!

This question has been asked a million times, but I still feel confused and people seem to disagree on this topic. I'm researching and learning, hoping to soon open a cottage food operation in Virginia, which requires that I use only non potentially hazardous icings.

I've come to the understanding that I can use dairy, fruit, nutella, cookiedough etc in my cakes, but I've also been told I can use milk and butter in my icing, but no cream cheese. This just gives me the heebie jeebies because I am SO SCARED of making someone sick since my baked goods are required to be shelf-stable. Currently, I prepare a Wilton buttercream of just powdered sugar/shortening/water/flavoring but I'd like to branch out a little. 

This article says in California, Buttercreams are now available as long as "no eggs, cream, or cream cheese" are involved. I've tried numerous times to see the recipes link on the Texas cottage foods site, but it gives me a user login error. 

It is my understanding that sugar inhibits the bacterial growth but I don't really understand if there's a limit to this. For example, is a cup of butter too much? Is buttermilk, or more than a few teaspoons of milk too much?

If the recipe in a cookbook says "this recipe will be good for up to 3 days" or "should be refrigerated after x time", does that mean it is not shelf stable?

I suppose by way of physical examples, would I be good to go with frosting recipes like this?

http://www.goodtoknow.co.uk/recipes/536932/rosewater-cupcakes-with-vanilla-buttercream
http://life-in-the-lofthouse.com/chocolate-cupcakes-with-oreo-buttercream/

Thank you so much :)