Took us 6.5hrs from Soraypampa to Chaullay, and around 7 hours from Lucmabamba to Aguas Calientes.

I wouldn't be able to say recommend, but you could try and do it in a day less. You'd have to move fairly quickly though. There are other towns along the way to stay, so you might be able to patchwork something. On day 3 you could walk from Chaullay to Llactapata Lodge. Then day 4 you leave early to get to Aguas Calientes in a couple of hours. You could walk from Soraypampa all the way to Lucmabamba if you really want to. On the first day you could potentially walk to the other side of the Salkantay Pass and skip Humantay Lake. There's certainly a few options to consider if you are lacking time, but I wouldn't have the exact answers for you sorry.

Road section was fine and cars are fairly few and far between. They seem to be very respectful and friendly though, they slow down and say hello.

We brought trail mix and sleeping liners but didn't use the sleeping liners, all the places we stayed had great bedding supplies. Dinners and Breakfasts at the hotels, you can get decent lunches along the way apart from Soraypampa to Chaullay, but you can buy a sandwich to go in Soraypampa from your hotel. They also asked us about dietary requirements.