I have downloaded the wallet. What is the difference between "Decred" and "Paymetheus Standalone" app?
How long is the minimum staking duration? Can I cancel the staking any time?
You should click on "Decred".
"Paymetheus Standalone" is for those who already had the wallet without gui installed.
EDIT: How long is the minimum staking duration? Can I cancel the staking any time?
From 24 hours after the purchase, your ticket can already be voted. About 50% of the tickets are voted within the first 28 days, allowing the purchase of another with the same coins next and thus multiplying the profit within 1 month.
It isn't possible to cancel the stake or sell the ticket. Your coins are blocked until it's voted. It can take from 1 to 142 days. It all depends on luck. About 50% are voted within the first 28 days, 80% within the first 2 months and only 20% take longer.