BRAKE SHOE ADJUSTMENT, for 9" Bendix CJ-3B, CJ-5, CJ-6

If the RH drums are not rubbing the shoe pad with the brake pedal fully released; then it is certainly not adjusted too tightly.
Essentially there is no need for clearance between the brake pad and drum considering that the pad does not rub enough to heat the drum while driving.
If the drum heats up without brake application, then its adjusted too tight.
Very slight drum heating is acceptable for new pads and will accelerate drum/pad mating.
Slight drum heating should dissapate within 5 to 50 miles of slow city driving.
Bottom line....DO NOT OVERHEAT THE DRUMS !

New brake pads will take up to 500 miles to properly mate to the drum face.
Or perhaps even longer if the drums are not turned true.
I suggest you use the brakes as they are for perhaps 50 miles.
Then remove the drums and inspect how the pads are forming to the drum.
At this time the new pads will show approximately 50% contact with the drum.
By inspecting the pads you will get a clear indication of how your particular shoe pads are forming to fit each drum.

The rebuilt brake system will attain its optimum potential when the pads are fully mated to the drum.
Roughly 500 miles useage.

As stated already, this is for the auto adjuster to work. When you back up and apply the brake it moves a lever that makes contact with the adjuster wheel and tightens the shoes up against the drum. N/A for the manual adjust 3B brakes.

Not necessarily. It could be that the left is too loose. Always start with the simple things first. Check to ensure you've got both sides adjusted the same (i.e. if you've got a little rub on the right, repeat on the left). It could also be a slight difference between the shoe linings - meaning that more lining is making contact on the right side (you could measure them to see if they are the same length and thickness). On a related note, are the drums all the same diameter? any drum turned to a larger diameter will have slightly less braking action until the liner is worn to match. It could also be that there is restriction in the line keeping full, unrestricted flow from going to the left side. Bleed to ensure the crud and trash are flushed out. There may be a restriction that won't clear and the line would have to be replaced. This would be tricky to resolve.

My manual says do the front shoe first, then the rear shoe. I honestly can't give you a reason why. It seems that if both shoes are adjusted to the same tolerance, it shouldn't make a difference. However, since it's printed that way, then that's how I do it.