You need Manaslu conservation area permit, Annapurna conservation area permit and Manaslu area special permit. If you are trekking in Tsum valley, you will need another special permit for Tsum Valley.
Here is the link for detailed information about permit.
You cannot trek alone in Manaslu since Manaslu resign is restricted zone; which requires at least two trekkers and certified trekking guide to do this trek. However, if you do not have a trekking partner, you can join the group in registered trekking agency.
No, you don’t need to carry any tent or mattress to do Manaslu and Tsum valley trek, since Manaslu resign is serves you fully as a tea house trek?
Manaslu circuit trek generally takes two weeks to be completed. But customize the trip as per your schedule; we finish it shorter/longer than supposed.
As Manaslu circuit trail follows the terrain from five hundred metres till 5200 meters, there differently are many steep slopes to walk past, which makes Manaslu trek fairly a strenuous trek in terms of physicaldifficulty.