Know the sound you want beforehand. Do you want the orchestral components to sound like an orchestra accompaniment, sound reinforcement, synths, etc.? So, if FA is your reference, then you should view the orchestra as another instrument that takes up space not only in the stereo field but in the arrangement most importantly. Yes, EQ sculpting is crucial, but that won't matter if you have your brass, strings, woodwinds, and percussion playing full blast while you've got a metal arrangement underneath at all times. My advice would be to really be conscious of what is the main focus of any given riff or section (i.e. Let the brass really drive home a melody and lay back on guitars to support the strings with the underlying chord progression). Being conscious of the dynamics in the arrangement, especially with as dense an arrangement as it's bound to be, will really help down the line in the mix.
As far as your other mix-related questions (saturation, parallel), I haven't run into any special techniques to use on orchestral elements. Be wary of your air frequencies since they will build up very quickly with all the brass and strings. Also, be wary of reverb build-up. I have also found that you really want to pay close attention to how the brass sits in your mix because if its too thin or not present enough, then sometimes the fortissimo dynamics in the low brass (baritones, tubas, trombones) will sound a little too much like farting instead of having that sharp metallic attack that we all love. Maybe it's just because I'm a former brass player, but I tend to leave more room for brass in the arrangement and mix.
Hope that helps a bit. Just my take on it.