You could take a flight from Dushanbe to Khorog. There is a 20 seater flight every morning to Khorog but its departure depends on weather conditions and the number of passengers. Tickets to the flight are sold a day in advance at the Dushanbe airport.
You could share/ hire a jeep from the jeep stand near the airport in Dushanbe to Khorog.
Same as getting in.
Rice, eggs, snacks, yak butter, bread, mutton.
Tea, surprisingly good coffee, and vodka. Yak milk.
A zealous policeman in Murgab may want to register you with the police or complain if you were taking photos. This isn't a problem, registration should be known well enough simply getting to the area.
There is some risk of altitude sickness.