You are describing dormant seeding, where grass seed is planted late in fall so it stays dormant until spring. Then as conditions warm in spring, the seed is already in place and ready to germinate. For northern Illinois, the time to dormant seed would be the last week of November. The seed should be planted so there is good seed to soil contact. In the event we get early snow, do not plant the seed over the snow.
Dormant seeding has risks, so if a large area is to be planted, you may want to consider waiting until spring to do so. Winter weather conditions are unpredictable. Ideally a snow cover is desired over a dormant seeded area to help assure the seed stays in place. Warmer than normal conditions without snow cover is one of the potential problems with dormant seeding.
Voles (field mice) can do considerable damage. About all you can do at this time is assure the lawn has been mowed right up until it stopped growing. Avoid having your lawn excessively tall and flopping over going into winter. Also be sure to keep cleaning up fallen leaves to avoid having lots of leaves on the lawn under the snow. Also rake away leaves and debris from under shrubs, especially low-growing shrubs like some junipers, as this provides cover for voles.
The late fall fertilizer application is targeted for about when the lawn stops growing but the ground is not yet frozen. The later we get into November for example, the less likely the fertilization will be beneficial. If in doubt, skip the application.
For northern Illinois, it is too late for effective use of herbicides. The weeds may still be green, but most likely will not take in the herbicide to provide control. Very cold weather could occur any day. For northern Illinois, September into early October is a more favorable time period for controlling perennial broadleaf weeds.
One big reason is the presence of warm and cool season grasses together in the lawn. Warm-season annuals, such as crabgrass and foxtails, died early this fall, leaving brown areas. Perennial warm-season grasses, such as nimblewill and zoysiagrass, are now light tan because they have gone dormant with cooler temperatures. Cool-season grasses, such as Kentucky bluegrass and perennial ryegrass, usually stay green until very late in fall or even early winter, depending on the weather conditions.
You may also notice areas within a lawn will vary in color due to microclimate factors. A sheltered area may be greener than an exposed portion, even if the same grasses are found in each. Areas with more available moisture may also appear greener in color.
If stored properly, most products will still be viable next season. Keep grass seed cool and dry. Fertilizer bags, if already opened, should be securely sealed so moisture is not absorbed from the air. Also protect bags from moisture. Pesticide products, in particular liquid formulations, should not be allowed to freeze. Choose a secure storage location away from direct heat or flame, and where children or pets cannot access them. Consult the product labels for more precautions.