Icons: I can add back icons, I'm sort of on the fence of how useful they are.

Crumbs: My plan is to keep all navigation in a tight, centered area vs. moving the eyes/mouse of the user all the way to the left of back to the top of the page. Or I could just add the crumbs back to the top. I think I'd use crumbs if they were in the header, but when they are in the top left, I tend to just click the back button on my browser.

Hiding values: not sure the value of having the entire value listed over making the list easy to read and browse. This comes down to what your doing. If I need a specific value change as a developer, I usually just go to "All Settings" and search for it, then click through. Discourse has a really nice search field that returns matching results from titles and descriptions. Inside the browse view though, it's not clear seeing the entire value on each object is important. Is there a particular workflow you have?

This is the search thing in Discourse and it works super well. As a first time admin, I used it like 50 times to find all the stuff I wanted to change without feeling overwhelmed by 500 options. I thinkkkkkk I could build a typeahead datasource and do this?