You can start with $10,000 but you don't get as much leverage as you would with over 25k. I think it's 5 to 1 up to 25k.
The training course is not required at any point. If you do take it, you can return for free as often as you like.
Demo mode is an option with the echotrader software. You can ask to have your account put into demo mode at any time if you don't have any positions on. You don't have to use it at any time if you don't want to.
I have no affiliation with Echotrade, I'm just a satisfied class B partner.
Corey