It's up to you. You can require students pay before being able to play, or we can bill your organization.
As many times as you like. The simulation is designed that you may lose several times before you finally win. This is true for all accounts.
Sign up for a free demo on the home page. You'll have the option to create an instructor account on the demo page. Or, just contact us.
You enter their emails in your instructor account. We automatically create student accounts for them and send them instructions.