Don't know about rivets, I'm sure someone will know...this site is a major brain trust.
There is a snap ring that holds the drive gear in place, it also has a spring behind. This is the only gear that connects the axle to the rotor assembly. It comes off first, then the bearings.
You will need a special socket that unlocks the bearing. Found one at Napa, it will have 4 teeth that are offset in their pattern.
Regular old axle grease will do fine, unless you want to spend more.