Answer: You can grow a wide range of plants in your area. When you select perennials, trees or shrubs look for plants considered winter hardy to USDA zone 6 or colder. You can grow just about any annual flower and nearly all vegetables as well as most (non-tropical) fruits.
Your lawn can be patched to cover bare spots. To do that, loosen the soil and work in some compost, then smooth it and seed. Press the seed into the soil to assure good seed to soil contact. Keep moist until the seed sprouts, this may take several weeks depending on the grass variety. You may need to sprinkle a thin layer of straw on the soil surface to shade it to help keep it moist. Or, you can use one of the patch kits sold where grass seed is sold.
For overall lawn success you need to run some basic soil tests to check fertility and pH, then apply fertilizer and lime as indicated by the test results. You need to check it by testing so you do not over or underapply nitrogen or lime.
Then mow correctly to encourage a thick dense turf: set the blades high and never remove more than one third the grass height at a time. This can mean mowing more than once a week. A healthy lawn will crowd out weeds and the higher mowing height helps shade out weeds.
If it turns out your lawn needs extensive work, the best time for seeding is actually late summer to early fall. Here are some publications from Cornell extension you may find helpful. (You may need to cut and paste the complete url into your browser to make it work correctly.)
Your local extension office is also a good resource and should be able to help you with the testing and interpreting the results. They should also be able to recommend the best suited varieties of grass, vegetables, and so on for your local area.
Enjoy your new yard!
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