This is probably the only one of your three questions I’m really qualified to answer …
As with all trend-following indicator combinations, the longer the timeframes you use, the “more signal” and the “less noise” there’ll be, and the more reliable the outcome, I think.
In a way, perhaps, the question we/you should be asking about this is “Is this observation [U]more true[/U], or [U]less true[/U], of Ichimoku [I]than it is of other trend-following indicators[/I]?”.
All the information I’ve seen about Ichimoku in books, courses, websites and trading forums has strongly suggested that it’s more true of Ichimoku than it is of other indicators: I’ve even seen “experts” in the field stating flatly that Ichimoku won’t work (worth talking about) over short timeframes. The general consensus seems to be that it’s far better on daily and 4-hourly charts, not so helpful with anything less than that, and of very little value at all on charts like ten-minutes and five-minutes. From my own observations, and those of a couple of ex-institutional traders I know, this consensus view is entirely mistaken, and my own feeling about Ichimoku is that “noise to signal” view (mentioned above) is actually [B]less[/B] valid than is the case with other trend-related indicators.
I strongly suspect that the widespread view of Ichimoku may still be influenced by its originally having been invented/produced to trade stocks from daily charts.
There are a number of very widespread [U]myths[/U] about the Ichimoku indicators, in my opinion, and it pays to be very cautious over taking advice on this subject: this is one of the specific issues in trading in which I think the consensus can very easily be a misguided one.
I trade with Ichi a lot. Like lexsy said I use it on the daily the 4hr and I do like it on the h1 but no lower than that. There r Many different ways to trade with it.
As for a EA for MT4 I cant help with that, I dont use MT4.