A few questions regarding realism

I posted a thread about this last week in the Scenario Creation subforum about a week ago to no response, I guess that one is more for problems regarding the scenario editor, and I don't feel this really belongs in The Jungle. Anywho, as the title states I've got a few questions regarding realism. I'm by no means a rivet-counter but I do like to have the scenarios I make be at least plausible (I.E. no trains on the Cajon Pass pulled by three SD40-2s pulling a random assortment of hoppers with some double stacks mixed in *glares at RSC*). This brings me to the questions.
1. What quantity and distribution of motive power would I typically see on the Cajon Pass, Horseshoe Curve and Donner, respectively? I've seen discussions on here where people have mentioned 8 locomotives as kinda a bare minimum, and then I see pictures of actual trains on the Cajon Pass led by just two or three ES44s/Dash-9s/ACXXXXCWs(I can never tell the things apart, heh). Wikipedia is of little help in this regard and to be honest I don't really know where else to look.
2. What kind of consists would I typically see on each route? I know Cajon sees a lot of intermodal traffic and Horseshoe gets a lot of coal, but what else? Do they get a lot of mixed freight, TOFC, etc? What about unit trains?
3. Would I see any freight on NEC, and if so, how much? Would P42s be a common sight on the NEC? Would common use of GP9s really be accurate for a 1990s rendition of Donner?
Sorry if any of these are silly questions, I figured there'd be few better places to go than here to get answers for them. Thanks in advance!
1. What quantity and distribution of motive power would I typically see on the Cajon Pass, Horseshoe Curve and Donner, respectively? I've seen discussions on here where people have mentioned 8 locomotives as kinda a bare minimum, and then I see pictures of actual trains on the Cajon Pass led by just two or three ES44s/Dash-9s/ACXXXXCWs(I can never tell the things apart, heh). Wikipedia is of little help in this regard and to be honest I don't really know where else to look.
2. What kind of consists would I typically see on each route? I know Cajon sees a lot of intermodal traffic and Horseshoe gets a lot of coal, but what else? Do they get a lot of mixed freight, TOFC, etc? What about unit trains?
3. Would I see any freight on NEC, and if so, how much? Would P42s be a common sight on the NEC? Would common use of GP9s really be accurate for a 1990s rendition of Donner?
Sorry if any of these are silly questions, I figured there'd be few better places to go than here to get answers for them. Thanks in advance!