The minimum trading amount is 0.01 lots, and the maximum is 5 lots, with an increase by 0.01 lot on every order.
The maximum amount of pending orders for all symbols at any point in time is 100.
The maximum allowed total volume of an open position and pending orders in one direction (either buy or sell) is 15 lots for each symbol. It means that if you have an open 15-lot Buy position, you can place a 5-lot pending Sell Limit order. But in this case you cannot place a pending Buy Limit order (since the total volume in one direction will exceed the limit) or place Sell Limit orders above 15 lots in total.
I trade Forex using my Bollinger Trend PRO mt4 indicator.