1.- Can more than one EA use on the same simbol ? bearing in mind a different name EA is used in MT5 : Can MT5 handle then several EA's?
It can be done with experts created with EA Studio. However, it works only in Hedging accounts. It can theoretically work in a netting account, but because of the FIFO rule, it is practically impossible.
FAQ: FIFO in the Forex Market
2.- If MT5 allows the modification and the EA uses it ,then MT5 is more effective in live trading account (LTA) situations?
Theoretically it is true, but practically it is almost the same. Every time the EA needs to modify a position it sends an order. The difference is that in MT5 it adds to the current position, but in MT4 it opens another position with the difference. The only benefit is thet when we close such a position, in MT it happens with one order, but in MT4 the EA sends a close signal for the initial position and for every additional one.
3.- If in MT4 the EA cannot modify the positions what is the possible outcome in a live trading account?
We made it working as if the modification is possible. It took us more than 10 years, but now it works like magic.
4.- I do not understand the way the modifications in MT4 simulations are handled (adding, reduccing, reversing ..)Is the logic interpreted: if the modification is addition then in the simulation the EA add positions? if the modification is Reduccions then the EA simulation will reduce positions for the same symbol? Will it be treated the same in both live or demo situations?
Yes, it works in the same way in the FSB Pro backtesting, the MT backtesting and the live / demo trading in MT4 and MT5. The concrete implementation of the different platforms is different, but the trading result and statistics is the same. As I said - magic ))