For tile customization, this is the place to start:
For default templates across dashboards, I think you can copy the json file and paste them into another boards "layout". Any CSS customizations you may have applied can be copied from the CSS file.
For multi attributes you can overlay tiles on top of each other. I'm pretty sure that's in the CSS guide I posted but there is a community app that might serve you well if you're not aware. He has also created a remote builder that may be of interest. You should give it a look:
