Do I need to remove or replace my catalytic converter?

No. This catback bolts directly to your factory cat. The connection point is where the stock system starts; everything downstream is new pipe and tip.

Will the stainless tip need polishing or maintenance to stay shiny?

Stainless resists tarnish and rust naturally, but road salt and brake dust will eventually dull the shine. Occasional wipe-down keeps it looking fresh; no special treatments needed.

What tools and hardware do I need to install this?

Installation hardware is not listed in this assembly. Bring basic hand tools and plan to support the exhaust while you work the bolts at the catalytic converter flange. Have your service manual handy for torque specs.