Do I need to weld this to my catalytic converter?

No. This is a catback system — it bolts to the outlet flange on your factory cat. Standard exhaust clamps and the factory mounting brackets handle the connection.

Can I install this myself with basic tools?

Yes. You'll need a jack, jack stands, wrenches, and possibly a ratchet set. The factory mounting points are unchanged, so there's no fabrication or drilling involved. Plan for a couple of hours underneath the car.

Does this system come with gaskets or clamps?

The system ships with the tube and tip. Double-check your connection points at the cat flange — you may need a new gasket if your factory one is worn, and have extra stainless clamps on hand for final assembly.