I love turbocharging, but I would not say it is safer. Proper engineering/tuning is what makes any form of forced induction safer.

Superchargers are less complicated to install, so while the cost of the kit may be similar, install is generally less money on a supercharger.

Turbocharging is hypothetically more fuel efficient than supercharging, because it makes boost from exhaust energy rather than off the crankshaft, but if you're doing forced induction on a Challenger, gas mileage is usually not the deciding factor.

With regard to pulley size, I could not see it listed online. The Magnacharger blog mentioned a "standard 3.8" pulley" on a Camaro, but there is no way to assume that they'd use the same size pulley for two different platforms. They might tell you the size if you contacted them directly.