Yes, you can get a GO Markets demo account with $50,000 in virtual money to trade with, for free using GO Markets servers to test out their trading services.
Click on the little gear icon in user settings (lower left of the screen), click on Notifications on the left menu, scroll down and turn "Message" off. Done.
Place the partner code 128979 into the "have partner code" box and you'll get your welcome bonus.
CFDs are not available in the USA due to local regulation and regulated brokers do not accept US citizens or US residents as clients.
The AvaTrade welcome bonus amount depends on your deposit amount. Using the partner code "128979" will get you the maximum welcome bonus available when depositing to your new account.