So over the last couple years since I've owned my Fairlane I've noticed a leak in the rear axle that appears to be getting worse since I drive it more than either my Grandpa or Great-Grandma did (and it's getting older).

So here is the situation. At first I thought the leak was coming from the diff cover gasket area, but after getting under there I noticed it is coming from the front (the pinion bearing area, is this right?). I looked it up in my Ford Shop manual for this car and this is what it appears to be I'm not sure if I have the terminology correct.

So here are my couple questions:

1). Are there a couple different gaskets in this area that should be replaced?
2). If so, can I remove just this front portion or do I have to remove the gears in the axle housing itself to remove this?
3). Any suggestions on how to do this? The shop manual has a pretty detailed disassembly portion, but it starts with basically tearing the whole thing apart, wheel hubs and all. I'm not sure I"m ready to tackle this myself without adequate garage space.
4). I couldn't find in my shop manual what the factory gear ratio is for this vehicle, it has a 223 3.7L 6cyl with a 1brl carb. All I could find was a range that didn't explicitly identify the gear ratio with the vehicle/ motor etc. If I'm going to go with a clifford intake/ headers/ and 4 barrel carb, I want to make sure my rear gearing can handle it. It appears to be in pretty good shape so far.
5). I'm planning on replacing the rear diff. gasket anyway, I also couldn't find what amount of oil was appropriate to refill with? Anybody know? I know the size of the housing matters, but I'm not sure what axle this is exactly.

Thanks any and all advice would be greatly appreciated!