First and foremost if you home was built before 1978 make sure your contractor has the paint tested for lead.
Second make sure your contractor is licensed to work on homes with lead paint, also know as RRP license.
All loose paint should be scraped, damage wood repaired or replaced, and all joints and holes filled with caulking. All new wood, exposed wood from scraping, and fill material need to be primed with a good primer. Peel bond is a great way to seal an entire home and is does a good job of filling small imperfections as it is a thick material.
Most contractors spray and back roll for consistent coverage. We recomend a minimum of 2 coats of a good house paint after proper perp work has been done.