Do I need to flush my cooling system before installing this radiator?

Yes. Run a flush and use fresh coolant—old fluid can clog a new radiator fast. Don't skip this step.

Which transmission version do I need—automatic or manual?

Check your transmission type first. The automatic version has coolant lines for the transmission cooler; the manual does not. Installing the wrong one means poor cooling or no transmission cooling at all.

Will I need new hoses, clamps, or a new thermostat?

Radiator only—hoses, clamps, and thermostat are separate. Inspect your current hoses for cracks or hardening while you're in there; many shops replace them at the same time.