the bowl is not in any danger of touching the water. a simpler way to melt the chocolate would be to microwave it with the cream and melt it slowly. i like having control over the heat and being able to keep an eye on what is happening to the chocolate.
if you want the hot chocolate to be rich and smooth without little tiny chocolate bits in it you can not use anything less than cream to melt with the chocolate. if you just melt the chocolate and add milk, you will not get a smooth consistency. the chocolate needs to bond with the fat in the cream and from 