Will this bolt directly into my rig without modifications?

Yes—this core mounts at factory bracket points. Your existing hoses and fan shroud will work without any custom work or drilling.

What's the difference between a two-row and three-row radiator?

The extra row adds cooling surface area, which means better heat rejection under load or in hot climates. You get improved thermal capacity without changing engine bay layout.

Does this come with new hoses or clamps?

The radiator assembly ships as-is. Reuse your existing hoses and clamps if they're in good shape; if they're cracked or brittle, replacement hoses are a smart move while you're in there.