Loke,
Can't speak for other engineers, generally, but
(a) a particular runway may, or may not, have a variety of sensible departures for the OEI case.
(b) the performance (wo)man's task is to find the one with the best weight (payload).
(c) one would normally expect an appropriate level of flight standards input but this certainly doesn't always occur.
(d) if the terminal airspace is busy it makes sense to gain some acceptance from the ATC people but this very often is ignored.
In any case, for most jurisdictions, ATC will accept an emergency call and do their controlling bit to keep other aircraft out of the way .. but it makes life easier if ATC at least knows what a particular operator's type/escape procedure is .. often forgotten by the procedure designer
(e) although many operators only look at the V1 failure case and leave the pilot to his/her own devices for other cases, a prudent procedure designer will cover failure at any point and climb to a level which gives nett clearance above the highest point .. 1500 ft is the nominal certification case but doesn't have much relevance to the real world if the particular runway environs require the aircraft to be driven to whatever higher level is necessary to clear critical obstacles. Again this doesn't happen with some operators.
The sensible pilot (particularly if you have an effective union representation) will make sure that he/she knows the operator's philosophy and approach to the procedure design activity.
Regretably all too often what I might see as being appropriate is not congruent with what some engineers might do ....