Having the Center Texts dim out for range checks makes it difficult to read the rest of the frame.
You have two options:
1. Assign your out-of-range status(es) to an indicator other than Frame Alpha.
2. Increase the alpha value of the out-of-range status so that the frame is less transparent when it's active.
Is it possible for the Center Icon to be layered beneath the Center Texts? I can still see the icons if an Unit Name overlaps the icon. I can't see the name if the icon is on top of the name.
Again, you have two options:
1. Don't use the Center Icon indicator for statuses where it's super important to know the name of the person it's on. For example, if you're a healer, you might use the Center Icon indicator for the Incinerate Flesh debuff, because you should respond to it immediately regardless of who it's on... on the other hand, it's probably not a good idea to use the Center Text indicator to monitor Lifebloom.
2. Install a plugin that adds extra icon indicators in locations other than the center of the frame.
I tried looking at the lua files but some of this stuff seems well integrated such as transparencies (which affect the entire object -- the frame).
Since the text is parented to the frame, it's not possible to (for example) reduce the frame's opacity to 50% while keeping the text 100% opaque. To fake the effect, you would have to set the frame backdrop's opacity to 50%, and then loop through all children of the frame and set their opacity to 50% as well. It's not something that will be added to Grid, but you could code it yourself if you really wanted to.