Newbie, probably basic questions

Hi everyone!
I'm new here but not entirely new to FS. I used to play long ago, but following that niggling feeling, I'm looking to get back into it, in a literal big way!

I've concocted a scheme to build a 737 cockpit (cliché I know, but the 737 is my favourite aircraft!). I'm planning a very DIY build; I know that I'll need to buy some parts, but as much as I can, I'll be aiming to build myself (like the throttles, the shell, the MIP etc.).

But a newbie question, one I'm assuming I must have glossed over while whittling away at online research is how these cockpits actually work?

I know a standard cockpit has a program like Sim Avionics or ProSim etc (the only two I can name off the top of my head) on one PC which is networked to a PC with FS on it.

• Is this for computing efficiency? I assume you could do this on one computer but it would be too much stress and FS probably wouldn't run smoothly...?
• Do these programs just provide visuals and interact with the hardware or do they have the systems modelled? (i.e. you wouldn't connect to the default 737 if it's just the former as it doesn't model the aircraft systems very realistically?).
• These programs have flight models and sounds available; is this mostly for the most coherent set-up? I assume you could link it to, say, the PMDG 737 NGx, but that this would be harder to set up and link all the controls etc. to the PMDG aircraft in FS?

My assumption, please tell me if I'm correct, is that the FS computer has a 737 plane on it, ideally with all systems modelled. If these systems aren't modelled then you'd essentially have dummy switches on your overhead etc. The FS computer feeds the aircraft data (location, speed, height, engine thrust) which the hardware/instrument PC turns into visuals which in turn is also listening for control inputs and the flicking of switches or moving of throttle levels etc., which it relays back to the FS PC, and so forth.

I think I'm basically confused as to the broad idea behind the setup, because if these programs only provided the visuals, then hypothetically you could do it on one, rather powerful, PC and simply undock the instruments each time (I know, that would be very annoying though!).
Hopefully this isn't confusing what I've written, but I accept it probably is! :oops:

Thanks!