I don't think any sealer is needed on the pan gasket. If you do use sealer, seal it to the pan and not the block - next time it needs to come off it'll be a mess if it's glued to both. And it's much easier cleaning gasket material off the pan mating surface than the block.
Sounds like good stuff you got - but don't think I've used it before. I have used something like it from NAPA that's gray and has worked well for me. A good way to use that stuff is to apply only a very thin layer, then put it in position with the bolts holding it to the surface, but not cinched down. That way the stuff can harden without squishing out all over the place. An hour or two later, or even the next morning, torque the fasteners.