Do these require adhesive or do they bolt on?

Mounting method is not specified in the product data. Test-fit the covers first to confirm whether they're designed for mechanical fastening or adhesive application before committing to installation.

Will these covers work if my truck has automatic door locks?

These are passive covers that sit over the handle exterior. They won't interfere with any locking mechanism or electronic components — electrical function stays unchanged.

Does the black chrome finish need to be sealed or treated after install?

ABS finishes like this are sealed during manufacturing. No prep, primer, or aftermarket coating is needed — install and go.