since you have that in your main.cfg

content_filter = smtp-amavis:[127.0.0.1]:10024

10024 is the amavis listeing port

No.

SOGo works fine with default iRedMail settings, i don't know why it doesn't work for you.
You can try to setup a virtual machine then install the latest iRedMail release, see whether SOGo works fine with default settings.

    // SMTP server
    SOGoSMTPServer = 127.0.0.1;
    SOGoMailingMechanism = smtp;
    //SOGoSMTPAuthenticationType = PLAIN;