Answer: Lawn grasses grow best in areas that are sunny all day long or for at least half the day, so you may want to consider a shade tolerant ground cover for the shady areas.
As far as redoing a lawn, late summer to early fall is the best time of year for that project.
I would suggest you begin by running some basic soil tests to check fertility and soil pH. Follow the test results to amend the soil with fertilizer and/or lime to adjust the pH. This will help your grass grow better. (A healthy lawn depends on good soil conditions.)
Your local Cornell county extension should be able to help you with the soil testing and interpreting the results, as well as recommend the best lawn grass varieties for your local climate and the soil in your yard. They will also have information about seeding, sodding, overseeding and lawn renovation as well as restarting from scratch.
In the meantime, you may find their web site helpful. You may need to cut and paste the complete url into your browser to make it work correctly.
Good luck with your lawn this fall!
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