I did the Camino in 2008. I wore Inov8 320's the entire way, not one blister, hot spot, nothing. I faithfully used Body Glide eachmorning before hiking out. The last 100 km are killers on your feet due to the fact it's mostly pavement.
I used my Gregory G pack the entire way, never was full. Carried weight was 12 lbs with bread and cheese, some snacks.
I had only 1 change of clothes for around town. Washed everything nightly. The albertgues are set up to do this. Some have washing machines and dryers. All have clothes lines. Just had flipflops for showers and town.
never camped, never wanted to, never needed to. Not too many places to do so anyway. Depending when you go, more crowds this year as it is Holy Year and the Pope will be in Santiago in July, so the places will be packed.
It does get cold in the mountains, especially when it rains/snows in June. You'll need some sort of rain gear. I don't care for ponchos, so I just used a TNF wind jacket I sprayed with DWR and that worked fine. I also had my rain pants just to keep me warm.
You'll need sunglasses and a hat, lots of sunscreen. trust me on this. The Mesa is bright and hot.
Water is plentiful, so I just carried 2 1 liter bottles.
I carried everything in my pack, brought it with me on the plane, and crusied thru customs, and never had any problems.
Treat your clothes with pemetrin!!!! Lots of bed bugs by mid summer. I used a Deuter hostel bag (can't remember the name) that goes to 40 degrees. Lucky if it went to 60, but it worked perfectly. Spain is hot. Hot. Hot.
Other than that...you'll run into enough towns to replenish for lunches, nibbles, that sort of thing. It is truly a great experience.
Yes, you'll need a knife for cutting bread, cheese, just about anything. And, you don't need poles. One section going downhill might help, but I never had any with me and just took my time. Otherwise, it's pretty easy without them.
BTW...you'll need a Pilgrim Credential to get into the albergues.