There are excellent answers to your questions in the below reference. No real difference in granular vs. liquid. Late fall (now) is a good time to fertilize. The section on dealing with weeds is worth reading carefully. It makes sense and brings up issues we don't usually think of. Also, the cold weather makes it more difficult to kill many types of weeds. Good idea to fertilize now and deal with the weeds next year rather than using a combined treatment.