Rather large lawn Twinsburg OH (Summit County), lawn being taken over by crabgrass. Lawn care provider would like to over seed now to otherwise improve turf and infill existing bare spots, some in shaded areas. Questions: 1. Is now an acceptable time to over seed and aerate, or would later in fall, or early spring, when cooler temperatures and added moisture prevail be preferable? Lawn will also be fertilised in fall and early spring and broadleaf weed control added to regimen. 2. My understanding crabgrass dies over winter and re-emerges in spring. Reemergent crabgrass killer will be applied in spring, assuming this is best way to control crabgrass? 3. Key issue, if lawn is over seeded and aerated now, or spring, would crabgrass killer also kill newly spread seed? 4. Most of lawn receives full sun, as noted, also considerable shade. Should separate seed choices be made to accommodate sun and shade, or would you recommend single generic seed? Thank you for your recommendations!