you can open an account at oanda and use a demo account.
If you want to deposit bitcoin, you can use 1broker for trading forex.
have you used 1broker? what I want to ask is after the deposit and trading when it is time to make some withdrawal, they do allow you to that right many forex broker give a very hard time when it comes to withdrawal.
yes, you can withdraw your btc whenever you like. As long as it is realised btc. ie, not locked into positions.