from research its known alien fighter carry 3 person crew,well if we already know a bit bout that ship our radars identify that and we shoot it down i think will be more realistic to meet 3 poor armed pilots no as it is now 5 well armed alien soldiers,so fighters usually no carry passangers 
otherwise craft identification help only aerial fight,maybe its not so important but it was nicely done in x com when downed ufo,s got also some casualties in crew
First lets clarify.
Most missions contain only 3 4 aliens - this is what u meant right?
U hope to have radar scanning the missions.... i believe that they are working on the pre-mission briefing to give more details somewhere in the forums... read it but cant remember where.
criusmac already pointed u to the proposal of having xcom like casualties (which are realistically possible and logical) for aliens who have been forced to land. Casualties which can be fatal / hurt - starting with less health than full.
Yupz. They are actually all in implementation / under work.
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Thanks for suggesting.