There's an ongoing debate in the US about using walking poles; most Americans leave them, many Europeans take them. There are benefits to using walking /hiking poles, with the biggest being that they provide balance and stabilization as you walk with the theory being because of the better balance you'll be safer walking/trekking. The poles also came in handy for determining depth of water to be crossed (streams, irrigation channels, etc.) and for retrieving fallen items.
I used poles for part of my pilgrimage and then stopped using them. My biggest issue was that I hadn't "practiced" with them enough. I wasn't fully used to using them for 4-7 hours a day and I developed terrible cramps in my hands.
There's no "right" answer to poles. It's a personal preference, as all gear choices are. But, perhaps it's more than a preference, some might say it's a philosophy of walking.
If you decide to use poles, start using them on your daily walks at home. Get some help (maybe at REI, Inc.) with finding the proper height. Get comfortable with the grips. Learn to alter your grip pressure. And, allow them to become extensions of your arms so that you become so used to them that when you walk without them they are missed.
Nothing compares to trying boots on and hiking in them. Here's some advice to get the most out of your shopping trip.
Select boots that are a half- to full-size bigger than you normally wear. The reason? While hiking all day, your feet will swell. And, if you do develop a blister or ailment, you'll want room inside your boots to accommodate bandages, extra liner socks, or even a tubular bandage (the latter were a wonderful solution for a foot problem I developed.)
Try on both the left and the right boots at the same time while wearing hiking socks, not cotton socks. Additionally, consider sock liners. They'll help you keep your feet dry, which is essential to healthy, pain-free, blisterless hikes.
Don't just walk a few steps and take them off. Walk around the store, continue shopping, and going up and down stairs if you can.
Ask about the store's return policy. It's important if you get out and hike with your new boots that if they don't fit you can return them. (Easy returns is one reason to truly love REI, Inc. They let you return just about everything--membership has its privileges.)
Don't just try them on and arrive in Spain with new boots. Get out and walk and hike in them. Get comfortable wearing them. Help them conform to your feet so you'll be ready when you arrive to begin your Camino and won't even have to think of your feet.
When traveling to Spain, wear your boots on the plane. You can replace just about everything else if the airline loses your luggage, but you don't want to start off your Camino with brand new boots.