Yes, upper Manaslu falls on the list of restricted area for outside travelers, in the past decades remained a forbidden and hidden country, then opened in 1991 but remains a restricted region for foreign visitors, to enter Upper Manaslu from Jagat village requires a special permit till it joins at Dharapani in Manang district. The restriction mainly due to the close border with Tibet / China where the route leads from Sama-Gaon and Samdu to the frontier of both countries.
Every village based on the itinerary for overnight stops, do have electricity with hydropower, and some places with personal solar power where guest can charge their electronic gadgets like cell phone, laptop, etc……..on paying some fees per hour of each item.
Very limited places, in Gorkha or Besisar town at the end of the trek, best is to change your money in Kathmandu for your conveyance. As you are trekking on remote areas of Nepal Himalaya, but to change cash of foreign currencies, where very few lodges on the route may accept to exchange into local Nepalese rupees. Facilities for ATM or other credit cards besides Kathmandu, in Besisar is available or in major towns on both way drives.
The chances are small and rare, as the altitude gains gradually by the time you reach over Larke-La pass or around high Manaslu valley you will be well acclimatized by then. As we have set the itinerary flexible with rest days to make it easier for trekkers to get acclimatize during walks and overnight stops at certain altitudes.
However, if some people get a slight headache from high altitude, they will soon recover having rest, drinking enough water that helps to acclimatize from the symptoms of AMS or altitude sickness. For very serious conditions, the sick person needs to be brought down to lower areas like Jagat or at Arughat village as well back to Kathmandu, by fastest means of transport either hiring a local jeep, the best calling for helicopter service to reach the nearest and best place with medical facilities and hospitals.
As you are trekking to the most remote part of the Himalaya, where facilities of good accommodation and food are much limited. From the village of Jagat, some lodges are very simple and basic, but at Lho and Sama-Gaon and Samdu the lodge are much better but with small rooms to accommodate trekkers, it will be clean and hygienic with good foods to enjoy from continental, Chinese, Tibetan, Indian and Nepalese famous Dal Bhat. It is best to carry warm sleeping bags and some snacks, like chocolate, biscuits, cookies, or dry fruits. Most lodge before Tilje and Besisar with common toilets and bath.
Due to the nature of rough road conditions, after leaving the main highway towards Arughat town and Soti Khola. Using comfortable coach or four-wheel drives like jeep or land rover for mountain and hilly roads. But from Besisar to Kathmandu on comfortable couch and buses or cars as per the size of a group.