If this is going to be your first system/install you be better of with a passive VS active.
the Polk amp you have makes 90w X4 @ 4ohms and 250w X2 @ 4 ohms bridges.
if you wanna go passive 3-way, the 250w X2 @ 4 ohms bridges is more then enough .
if you wanna go active, you can get another...