EGNM,
I don't think you want too complicated an answer, so I'll not give you the benefit of all my performance knowledge (otherwise we could be here for over 3 minutes).
The simple answer to your question is 'no'. Basically, there are two cases; one has you getting airbourne after V1, the other has you stopping. In the stopping case you must, obviously, be able to stop before eating the lights at the opposite end of the runway (and for the purists, yes, I know about stopway, clearway, EMDA, ESDA etc but I said I'd keep it simple). So, there must be enough runway to accelerate to V1 and then stop. In the 'flying' case you must be able to continue the takeoff after V1, roatate and be at 35ft (15ft if it's wet) at the end of the runway at V2 (safety speed). So those are the basic requirements and leads to the calculation of your field length requirements.
Now, to the 2nd part of your question. Yes, you can reduce engine wear. Assuming for the moment that it's nice and flat around your airfield and there's not a great big aerial on the extended centreline, then we'll keep it simple and say the field length requirements are the limiting factor. So, let's imagine for the weight of your aircraft you need 1500m to either get airbourne after V1 or stop at V1. With your 2500m long runway you can reduce thrust, thereby saving on wear and tear, fuel and noise (although the greatest gain is in wear and tear). This is normally done by 'fooling' the thrust management computer (TMC)into thinking it's hotter outside than it really is, so it thinks it hasn't got as much thrust available. During your performance calculations you, as an example, used 15 degs to come out with your 1500m. Now you go back into the graphs/tables/computer and extract the temperature at which you'd actually be able to lift your aircraft weight using 1500m and it may come out with something like 45 degs, which you then tell the TMC that's it's 45 degs and it gives you the takeoff reference thrust for that temp (which will be less than that at 15 degs). This method of reducing thrust is known as Assumed Temperature and is used every day by many ailrines etc. Equally, many just use a fixed derate (10 or 20% of thrust) but this does not give the same sort of engine life savings taken over a long period.
As I said, this is not all there is to it by a long chalk and I've tried to keep it simple, so no barracking from the cheap seats. There are more calculations that go into determining max takeoff weights and the amount by which you can reduce thrust for takeoff but that's the basic idea......I think
