Powder does go bad, your stuff is just about 20 years old and that is ten years beyond the age that Federal says is the shelf life of their ammunition. They are being conservative, but you know, I have tossed a bunch of mid nineties powder. And so have others.
Powder that is fuming nitrogen dioxide is highly dangerous, it is ready to auto combust and burn your house down!
So, with your powders, break the seals and sniff the stuff. If it has has the slightest vinegary, bitter smell, toss it. If the smell knocks your socks off, pour it out immediately. Nitrogen dioxide turns into nitric acid gas and that is ungodly horrible.
If the powder has a neutral smell, it is past its mid life and it is about time to shoot it up.
In so far as reloading manuals. When I called Accurate Arms and Hercules, they blended their powders so the pressure curves were within plus of minus 5% (or 10%) of their standard for that powder. That was so you could use the same brand powder and reloading data that you created eons ago. However, powder companies can change their formulations at will, so it is best to find reloading manuals from the era of your powders and use that data.
This is an outstanding site with free old manuals:
http://marvinstuart.com/firearm/Manuals/Reloading/Reloading Manuals/