One by one... so many questions... brrr...
I'm not a film composer, but I do work for media, so I probably can offer some serious insight here...
1. It's better to use a sequencer rather than a notation software because they work in different ways. A notation software will primarily produce a score, while a sequencer will produce... sequences (in other words listenable music). The difference is that no matter how hard Finale or Sibelius try they STILL cannot offer the control that a sequencer offers over samples, in which case the result of digitized music coming out from a sequencer (Cubase) is better than that coming out from a notation software (finale).
And there really is no argument against that, no matter what people here will say (Tokke will chime in in favor of sibelius)... Cubase and other sequencers cannot produce decent scores and notation software only produce mediocre recordings.
So...
If you plan on having your music performed live (fat chance, but perhaps you have the means), then by all means use notation. If you end up using samples to produce your final recording then you WILL need to use a sequencer at some point. Perhaps not in the beginning or the actual composing process (because you may be used to composing in notation), but later on you will need to import your stuff in a sequencer to sync and make them... sound good.
2. Film scores are hard to find. For free they are illegal to find, so you won't be getting any replies here. Hal Leonard sells some scores and perhaps there are others who do that, but other than that the orchestral film composers (even the AMAZING Williams) was inspired by the classical composer, who you don't seem to appreciate too much. so studying the classical scores (which may be available in IMSLP, for example for free), would give you plenty of insights on where the film composers got their ideas.