Most committed soapmakers end up with a broad collection of both decorative and plain molds and they use them all. These molds meet all my criteria. They are durable, they are see-through, they provide a slick finish, and most importantly, the possibilities for design are unlimited. I like to use beeswax. Wax will make the soap less clear.
Alcohol can make the soap more drying and impart an odor.
This will also make the soap softer. This will make the soap clearer and softer and can make it more sticky. I suggest you consider adding a bit of commercial detergent or shampoo if lather is a big issue for you. Embedments are melting. Temperature of the soap you pour over the embedments is too hot, or embedments are too thin.