Here's what I know... or I believe to be relatively accurate, I'm sure someone will correct me...
9000 were considered Recording Custom
8000 were considered Touring Custom
7000 were considered to be the Stage Series... but then there was also a lower end 5000 series, not completely sure what they're comparative to.
I actually own a set of 7000's, my first set actually, I still own them and gig with them now and again, great sounding shells, great construction. I believe they're a mix of Birch/Mahogany.
From the looks of things that snare may be missing the proper strainer "bracket" that's meant to rest the snare wires on. At least my snare has it, the wires extend past the width of the drum, hence the larger cutaway in the bottom hoop.
HAH, I just googled "Yamaha 7000 snare" and the first result was a thread I started on PDF in 2005! There are pictures of mine (pre-clean) here: https://www.pearldrummersforum.com/showthread.php?73961-Tips-for-cleaning-this-snare-drum
Also here's the catlogue image about the 7000 series snares: http://www.vintagedrumguide.com/images/catalogs/yamaha/1978_yamaha_catalog_19.jpg