I suppose I can mix up the strings and voices but there is a lot of stuff in there. I've never done an arp but it might help in the choruses to cover the multiple parts....
As you said there is a lot of stuff in there ... What I use is a simple approximation but it can be a start. For the strings I use 546 Adagio Tutti 8ves modified to have a longer decay (more reverb) so as it's not as "dry". I couldn't figure out how to setup the arpegios I needed for the strings in the second part (starting with There is no pain ...) so I setup 4 songs of 4 notes which I assigned as Riffs to 4 keys 
. For the trumpets/brass sound I use 1168 GothClimax. And for the little bells after "just a little pinprick" I use another 3 notes riff based on the 506 bells again with more reverb.
It's a start. Hope this helps !
