Anyway this is a combination that won't be used because users cannot be added to that properties file.
Not really sure what you mean here - the point of the properties files is that users can be added to them.
If no security is used for remoting I only get random password in my custom login module.
Yes that is correct, if you disable security for remoting there is no username or password that can be sent to the login module.
In your config I see the following line: -
remote.connection.default.password=c4ca4238a0b923820dcc509a6f75849b
What is this password? This property need to be the plain text password - not the pre-hashed password from the properties.