The main difference is in installation; batt insulation comes in pre-cut pieces, while roll insulation is installed by rolling it out between ceiling joists.
Attic insulation should be about 10 to 14 inches deep, achieving an R-38 level, depending on the insulation type.
Drying time for wet insulation depends on type, ventilation, temperature, and humidity. If it doesn't dry within 2-3 days, it should be removed to prevent mold and wood decay.