Will this condenser fit without removing the radiator?

Access depends on your specific model and engine bay layout. Factory mounting points align with OEM locations, but you'll want to check your service manual for condenser removal and installation steps before starting.

Do I need to flush the AC system before installing this condenser?

Yes. A system flush removes old oil and contaminants that can damage the new condenser. This is standard practice and worth doing right the first time.

What about the refrigerant and expansion valve?

This is the condenser unit only. You'll need to source the refrigerant separately, and the expansion valve remains part of your existing system unless it also needs replacement.