IB provides free 15min delayed data, but this will not be accessible through the IB API. In order to access both real time market data as well as historical data, a corresponding market data subscription has to be in place.
Market data can be accessed both through the IB paper trading account as well as the live trading account.
The paper trading account has one single username assigned to it. The live trading account can have multiple usernames.
For each username (live account & paper trading account) only one session can exist at the same time. If you login with the same username on a different machine the other session will get logged out.
If the live account username (that is sharing its market data subscription with the paper trading account) is currently logged in, the paper trading account doesn't get market data until the live account is again logged out.
If a client wants to login to the live trading account at the same time that AlgoTrader is connected to the paper trading account, he has to create a second username under the live account and purchase additional market data subscriptions for that username.