A visa is required. Full details of the procedures involved will be included in pre-departure booklet.
There are frequent international flights to Dushanbe. It is very difficult to obtain public transport from Penjikent or Dushanbe to either Iskanderkul, Artuch or Shing. In Tajikistan taxis are expensive and fuel is scarce. It is probably best to hire your own vehicle and ideally you should make arrangements in advance with the help of a local agent or operator.
The Fann Mountains are gradually becoming a more controlled and protected area. The government is in the process of setting up a system of entry permits which are presently reasonably priced. Details of permits required and entry procedures are best obtained via an agent or from the Tajik Ministry of Foreign Affairs.