Create Expert Advisor from Custom Indicator -- 2

I possess a custom indicator that gives sell and buy alerts. I'd like to create an EA that converts these alerts into orders as follows: - when a buy signal shows, it closes any open/pending sell order and opens a buy order. - when a sell signal shows, it closes any open/pending buy order and opens a sell order. - there is always only 1 trade open (buy or sell). -when the ea is launched it must check if there is already an open order created by the EA earlier to make sure not to open more - ideally it also allocates lots according to % of equity or set risk amount (i.e. $100) and creates SL with % from entry NOTE: I purchased this indicator in a bundle with others. I only possess the ex4 file. Please contact me if any further information is needed .