Do these seat covers require any adhesive or fasteners to stay in place?

Installation method is not specified in the product data — test-fit before committing to fasteners, adhesive, or straps. Voris-style covers typically rely on tension and tucking, but confirm your specific vehicle's needs before assembly.

Are these covers pre-sewn as one piece or do they come apart by seat?

Construction is not confirmed — verify whether the set breaks down by individual seat (driver, passenger, rear bench) or arrives as a assembled unit before installation.

What's your return window if these don't fit right?

Check the site's standard return policy for the exact window. Since fit is critical with seat covers, measure your current seat dimensions and compare them to the Voris-style spec before ordering to avoid returns.