I agree with you, I too am using all custom equipment and would like to utilize Named Expressions as well. Sadly they just do not work. However, they would need to be a lot more advanced in order to work for my needs. For instance, if I create an equipment it will likely need to have different levels within it, like steel and anchor bolts as examples. Therefore, having a single named expression reference an element template or specific level would never work for what I am doing or, in my opinion, what anyone would do with custom equipment. I guess that would depend on the level at which you decide to separate components as equipment.
Transparency does work. I currently have all piping element templates working with the insulation set to transparent.
If you need help getting transparency to work with your piping insulation, let me know.