I've read that I should "wet the hopper" in a large metal percolator (35-100 cuppers). I think that just means I shouldn't put the coffee into a dry pot, but I don't know what good that does me. Is it possible (or useful) to bloom 6-8 cups of coffee grounds the way I would with a drip coffee maker and how would I go about doing that?
You would bloom a large percolator the same way you would bloom in a pour over. Of course, there are different ideas about how to bloom for pour over.
From the website Hand Ground:
Use a 1:1 coffee-to-water ratio for the bloom
"Bloom the heck out of the coffee" with a 2:1 ratio
Stir the bloom
DON’T stir the bloom
To bloom coffee in your percolator go through your normal routine except you will be adding less water. If you are using a 1:1 bloom subtract the mass of the coffee from the water you add to the reservoir. If you are using a 2:1 bloom, subtract twice the mass. Once you've added the coffee you will bloom it by pouring hot water evenly over the grounds. Because a percolator won't fit nicely on many scales, measure out your hot water first; this is probably easiest achieved by pouring into a pitcher on a scale until you've attained the equivalent mass of the coffee (or double). After pouring into the grounds, wait a minute. If you want to stir, stir. This might be a good idea because you are working with much more coffee than a standard pour over.