First off i'd like to point you towards:
Musicians' Corner - AVForums.com
A lot of people visit that board for more production specific matters, you might get a better response there, so possibly as for a mod to move this thread there for you.
Also regarding the music, personally i'd go for a nice slow quiet cello background, a fast violin lead (i dont mean a fast melody - fast violin) would go well towards the start as you build in bring in some nice brass, piano and more slow strings, spicattos are good for dramatic effects, a nice bassdrum sample would be good as well as other percussion hits, but don't use too much of them.
I imagine the main part of your result will be how you piece the instuments together, all orchestral music is sequenced so that the instruments played together compliment each other.
Also I imagine you have to write it as it might be played for an orchestra?
So try not to over-do strings as to require 100 string players, layer some or use an ensamble but don't over do it, try bring in variation, woodwinds etc can give just as good effect providing you have decent VSTs
Use your effects such as reverb to your advantage too; to emulate a good hall.