Will this bolt directly to my stock catalytic converter?

Yes, this catback design connects at the factory cat outlet. No modification needed on that end. You may need to verify hanger and bracket clearance once on the car.

Do I need a new gasket or sealant where it connects to the cat?

Confirm with your service manual or test-fit first. A quality exhaust gasket at the cat flange is standard practice, but not confirmed as included here—pick one up if your current gasket is worn.

Can I install this myself with basic hand tools?

Bolt-on catback systems are typically a weekend job if you've worked under a car before. You'll need jack stands, a socket set, and patience. If you're new to it, a shop can bolt this in under an hour.