I've done lots and lots of long distance walking, and for that amount of walking I personally would go for trainers UNLESS I knew I needed my footwear to be waterproof and/or non-slip (up and down terrain). Ooops, just saw it involves steep descents/ascents - definitely boots then.
I also wouldn't wear woolly socks, I'd wear the two-layer versions of thousand miles socks (I found the single layer versions are a bit '9-mile-sock-of-blood').
Whatever you choose to wear, if you have any tendency to flat feet, I would recommend an arch support, as long distance walking is hard on your arches. I use the blue ones from Salford Insoles, and recommend them to patients all the time. They aren't much more expensive than the ones you buy in Boots (you have to buy them online), but they come with a lifetime guarantee.
Never take off your boots or shoes until you get to the end, even if you think you are blistering, as you probably won't get them back on. Use vaseline over your toes before putting on socks if you find you have trouble with blisters during training. Hopefully you are training, because that is the best way to break in/check your shoes/insoles/socks combo, especially if you aren't used to distance walking, and especially as your walk involves steep parts. It probably won't affect your ability to complete the walk, but it will affect your enjoyment of it.
Laces - look online for how to tie your laces so they don't loosen (and then your feet don't move, so less blistering.
Take more water than you think you will need for your hike. I remember relying on the water-stops during a Moonwalk and ended up not able to find water from 18 miles to the end - I'd never had brown urine before :-( Also flapjacks etc for energy - you won't feel like eating loads if you are walking fast. That said, a hike may be less fast than the sort of walking I do?
Other things to take - sunblock (apply sunscreen before setting out) and hat if it is looking really sunny and painkillers just in case. You will love it, have a great time!