From my perspective:
Depends what you mean by "emotional", and on who the EIE is. Would you call David Cameron "emotional"? Bono? Mena Suvari in American Beauty? Freud? Oprah Winfrey?
Probably not.2. Is it likely that an EIE/Fe-leading type would retreat somewhere private when feeling upset, angry or down because they are uncomfortable with displaying these emotions in public?
Unlikely. This sounds like a person with weak Fe (and thus Fi). However, if the EIE realised that remaining expressionless was necessary to achieving their goals, then I'm pretty sure they could use their Fe-related skills to do this.3. Would an EIE/Fe-leading type, when being berated or told off by someone, not necessarily a superior, remain expressionless and stone-faced throughout the tirade; becoming absolutely frozen, then turning and attempting to place as much distance between themselves and that person? And only, when a period of time has passed, be capable to expressing that anger, usually to sympathetic parties?
Again, the above applies in terms of the EIE applying their skills. However, the EIE is more likely to use expressionlessness as civility than they are to remain stone-faced because they would rather not reveal their emotions publicly.4. Would an EIE/Fe-leading type display their negative emotions, or are they more likely to hold these in, particularly by minimising their facial expressions, in remaining civil?
Absolutely. This is pretty characteristic of Fe ego types, if I'm not mistaken.5. Is an EIE/Fe-leading type likely to hold back their criticisms of someone they find incompetent when that person turns to them for sympathy and try to both reassure them whilst expressing their concerns diplomatically, though they do not necessarily like this person?
FTR, if you were IEI, that would make life even better. It would explain why I am attracted to your character, unefille.