Not knowing the chassis GVWR but,
75/140 Synthetic Approx 8.5 pints
Ford says 80/90 oil. Approx 24.5 pints.
Look under your rig. If the rear axle looks like it is about the size of a pickup, then you have the Dana 80, if it looks quite large it is a Dana 135.
Personally, I use nothing but synthetic rear axle oil.
Brake fluid, Ford says High Performance DOT 3 brake fluid. DO NOT TRY TO USE DOT 5....
As for you bleeding then, yes you can, but no more than it will cost, it is not worth the effort. Make sure the person who bleeds them for you has a bleeder with a bladder between the air source and the fluid. Some of the cheep ones applies air directly to the fluid. Do not use this type of bleeder.
Brake Fluid 1A