Polk MC80s In-Ceiling - Grills/Rotatable?

I have two MC80s in my ceiling, both directly above the left and right sides of my couch for my 5.1 setup. The speakers were installed in 2014 and have served me well. Eventually, I might swap them out for something more high-end, but since they're only used for the two surround channels, I'm not too concerned.

Anyway, I've been toying with the idea of removing the grills. None of my speakers and sub have grills. Obviously, the grills help the speakers blend with the ceiling, but I'm not really looking for that. I'm guessing I can probably yank them out with a putty knife or paper clip, but is it safe to use ceiling speakers without the grills on? I don't really know the rules, since I'll technically be exposing them to the elements. I wasn't sure if there was a risk involved in running them without their grills.

Another question. Do you know if there is a way to rotate the speakers? I tried to rotate the plastic "housing" ring in the ceiling, but that's pretty firmly in place. But can the speakers themselves be rotated? I don't need to tilt the tweeters, but I want the speakers to sit in the same "position" if that makes any sense.

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