Welcome to the Bolt!
Pulling those bolts in front of the pinion gear will allow you to change the seal, but wont allow you to pull the pinion assembly. Youll have to pull the axles and unbolt the front section of the differential to get the pinion gear and its assembly apart. I suppose you could probably do it without taking it out, but itll be much easier with it removed from the housing.
That bolt on the side goes through the housing and runs against the back of the ring gear. It has a small thrust pad at the end that basically prevents the ring gear from distorting if your towing or pulling a very heavy load.
If you dont have a maintenence manual nows the time to buy one. Most of the bearings you should be able to get through Napa or your local parts store, although youll probably get a much better deal through a bearing supplier. I use
Applied Industrial Technologies.Jeff