While you don't say if these are for music or home theater use, they do appear a little large for either use - it's not that big of a room. While 9 inches sounds good, they're better suited over a dance floor.

Generally, 6 inch coaxial speakers, backed up by a sub-woofer, are fine for music in the ceiling and home theater in the walls.

Usually, you can just use the grills that come with the speakers and paint them to match the surface.

The actual speakers are 6", but the part that is visible (I guess it's the casing or housing) is 9.5" and that's the size that will be on the ceiling. This seems large, right? thanks.

Large is in the eye of the beholder. As a sound geek, all I can say is, you should see my speakers. :-p

Seriously though, if you want good sound it is very unlikely you will be able to make the equipment completely disappear.

I have a room with 4 6' (with covers, about 9") ceiling speakers in a 18' by 25' room; for tv watching, it is good enough.
Upstairs, I have 4 ceiling speakers in an area of about 20' by 28'; it's a kitchen/family room (quite open actually) and it is also good enough. Of course, the other room ceiling speakers can back the kitchen area up if need be and I've never had to do this for loudness (a 20 watt/channel amplifier).

Yes it is quite enough