An H60 should be fine for stock speeds, but seems a little overkill.
Decent air coolers will rival an H60 for less money. An H60 is a ~$60 cooler, and you're really just buying it for bragging rights (ie, I have an AIO), it's not a top-tier performer at all. A comparably priced, well reviewed air cooler would be the route I'd suggest.
As for single 120mm vs 240mm, 280mm, 360mm Rads etc, it's cooling capacilty. More fluid, more airflow, more space on the Rad to dissipate heat.