Inca Trail, Did it about 5 years ago and would certainly recommend it. Peru's a super place, Cuzco in particular.
The Inca Trail is 3½ day walk, with some great views. Gear? well I wouldn't worry about what brands. Normal UK walking gear will do, a decent waterproof, fleece and a base layer.
That said I did wearing normal cotton t-shirt, shorts and a cheap waterproof. I went over xmas/new year when it's wetter, but doesn't get too cold on the evenings - wasd ok with a sweater.
I went on organised trip then. Though I don't believe you can do independently now, there's sure to be local outfits in Cuzco that will organise it for you.
I'd also recommend trying white water rafting on the Urambamb while you're there.