You will see more fellow walkers in the Le Puy - Conques section, and the numbers will tail off after Conques. This is true for every time of year, but will be especially true as late as you are running. There are two-week school holidays in France in mid-October, and some lodgings will close during those holidays; others will close afterwards. At the end of the month, Nov 1 is All Saints (Toussaint) and many lodgings close until Easter (Pascal). All of this is to back up what Falcon said about calling ahead -- even two or three days ahead would not be inappropriate at this time of year. Even if the lodgings are scheduled to be open, per MMD, if they have no bookings, they may take off to visit the grandkids. Be sure to enlist the assistance of your gite hosts for meals and onward reservations.
Weather will be changeable, as it always is during shoulder seasons. You will have some hot sunny days as well as some chilly damp ones. The elevation is lower after Conques, so you shouldn't encounter snow.