You are responsible for your data fees, but Helios will deduct it directly from the account balance they give you. You are not required to pay any out of pocket expenses.
Exchange fees will be deducted from your account balance immediately upon receiving your account and every 30 days thereafter. Please note that this will affect your account balance.
If you prefer, you may also choose to pay the account fees out of pocket and Helios will hold that as a credit toward your account to be repaid in your second month of live funding. This way, you will be able to trade with your full balance and won't have a deduction in your account balance at the beginning of the month.