Does this bolt directly to factory mounting points or do I need to fabricate custom brackets?

This uses factory rocker and core support mounting points. The included brackets attach at those OEM locations—no custom work needed.

What hose size do the inlet and outlet tanks accept?

Tank port sizing not specified in the product listing. Measure the tank ports directly or contact the supplier with photos for exact fitting recommendations.

Is the core aluminum or does it need to be painted or sealed before installation?

Material composition not confirmed. Inspect the core when it arrives and test-fit it before committing to any finish work.