Depends on how thick the slurry is. Once it thickens, it shouldn't matter how long it sits to fully dry.
No idea. I'd spin it, and check it, spin it and check it ( empirical testing), do a small test run, then when i think i got it right, do a larger test run non stop. Then let it fully dry.
A jig would simply be a gear train with mechanical pencil erasures as the spinners variable, speed dc motor.
If I were doing the testing, I would FIRST, do some testing outside the cases, and in very small batches, to get the slurry viscosity, understood, and the time for the solvent to dissipate, understood, as well... Then test the sensitivity of the now dried Primer Compound, to shock... Work out those properties, so you understand them, well, before trying to prime any used cases.... Then go for a few test Primed Cases, with just some fast Powder, like. Herculese Bullseye, and a wax plug.... To make sure that your Priming Powder application procedure are good, an are hot enough to ignite the Powder, every time... Once those things are down pat, then work up a Loading with real Lead Projectiles...
Then to establish the amount of priming slurry to put in the case before spinning it up. Sounds like the spinner is the easy part, eh?
Yes, as i said, it would not be difficult to build. The kit itself should give instructions for use and expected results as well. (Mix, measures, and applications)
Yep, You are essentially opening your own manufacturing line, and understanding the "Process" is mandatory if you want a quality Product coming out the far end...
Agree the directions should be complete, and very likely do NOT need a backyard centrifuge. Gotta wonder why that idea came up --
BT, my Strike Anywhere matches still explode when shot from an air-rifle to a brick wall. Just Sayin.