Static nodes don't work for me. The only way to get it back going once it's stuck is to delete everything and leave only wallet and conf files. But it gets stuck again after a while.
I read that those nodes helped for a few others though

Maybe I do something wrong.
What do I have to put in username and password?
1. my pc user username and password (limited user)?
2. administrator username and password for this pc?
3. any random username or password?
rpcuser=username
rpcpassword=password
rpcport=9456
port=9455
or maybe I have to unlock my wallet for staking ONLY after it has fully downloaded blockchain? I read it in some other PoS coin...
username and password doesn't really matter too much but you want to have as strong of a password as possible, for the most part you will never use it directly as it allows your RPC functions.
In your PayCon.conf file add put this in there, these are static nodes I have setup for extra connections.
listen=1
daemon=1
rpcuser=*yourusername*
rpcpassword=*yourpassword*
rpcport=9456
port=9455
rpcallowip=127.0.0.1
addnode=107.170.179.27
addnode=162.243.155.75
addnode=128.199.231.68
addnode=178.62.151.188