It’s very popular nowadays, and it gets crowded especially when cruise ships are in nearby La Spezia port. If you w at you can check the cruises’ schedules online. In October it is probably less crowded than in summer, but again the cruises affect the situation the most. The most popular town is Vernazza, so that place gets particularly crowded when visitors arrive. Monterosso is the largest village, so it will have more accommodations and restaurants.
Via dell’Amore reopened this month. You can walk it only in one direction eastward from Manarola to Riomaggiore (it’s a “one way” street now) and your ticket is valid for a 30 min. window within which you must cover the distance. I don’t know what happens if you take longer. I heard that they will throw you down the cliffs and give you to the sharks, but I don’t know if that is true.