Orientation for digital beginner

I am new to using digital control for music systems and am looking for some orientation and guidance on how to go about setting up my system.

* I have a large multi-building estate and want to supply music to different areas, including outdoor areas from a NAS.

* I would like to have the highest possible music quality given the digital control constraint

* I do not need or want streaming, just the NAS/computer. If I wanted to stream something, I would obtain the stream from a Linux-based computer, not a hardware streamer. None of the components of the system can be internet connected.

* I don't really use phones or tablets and in any case I have guests and I am not going to tell some guest, "Oh we have to spend 45 minutes installing this app on your phone so you can play music in your room." That's not going to happen.

* Control will be via Android-based kiosk-style touch panels installed in strategic places in the walls. I am an expert Java programmer, so custom programming is not a problem.

* I have no budgetary constraints 

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So, the questions/problems/unknowns I have are the following (please understand I am totally new at this, so some of my ideas might be totally wrong):

(a) My guess at the way things work is the following:

    - there is a Linux computer that is the brains of the system, it runs "management software" like LMS, the brain computer takes inputs from the touch panels and makes the following outputs:
      (1) it tells the touch panels what to display and receives inputs from the touch panels
      (2) it tells the NAS what to stream and which DAC to stream it to
      (3) it tells the pre-amps what volume settings to use and which speakers to turn on or off

    - there is a NAS that is connected via ethernet to 2 or 3 DACs 

    - there are 2 or maybe 3 DACs (I assume a DAC can just play one piece of music at one time, so if I want up to 3 different music streams at the same time, then I need 3 DACS), the DACs output analog sound on either RCA or TOSlink (??? see question (e) below) wires that go to preamplifiers

    - there are preamplifiers for each room or area. So, if I have, say 12 different music zones, then I need 12 pre-amplifiers and 12 amplifiers and 12 sets of speakers, they take analog input from the DACs and a digital control signal from the brain computer, and output a pure analog power signal to the speakers over RCA wires

 (b) So, my first question is what pieces am I missing? For example, I have read that just having management software like LMS is not enough, there is other software that is needed. Not sure what this might be.

(c) A big problem is trying to identify high-end DACs and Pre-amps that will take control from the brain computer. For example, I was looking at NAGRA systems and their pre-amp just has knobs on it. You can't control the volume of the pre-amp from a computer as far as I could tell. What are the highest quality audio components that do support digital control?

(d) Different DACs seem to have much different features. So, the brain computer needs to tell the DAC stuff like "Stream to area #8", so if I have, say 12 different areas, then the DACs need to each have at least 12 outputs OR there has to be some kind of special switch with digital control, similar to a pre-amp except that it just switches analog signals, not power images. Kind of like a pre-pre-amp. Not sure if such a thing exists. If it does exist what is it called?

(e) Most DACs seem to have RCA outputs. I have heard of things like SPDIF and TOSlink. Are these analog alternatives to RCA? If so, do I want a DAC that supports say TOSlink or SPDIF?

(f) I have heard that distance can be a factor in sound. So, for example, if I have 12 pre-amplifiers/amplifiers, one for each room or area and they are all in the basement, then I might have wires going 100 feet from the pre-amplifier to the speakers. Will that signfiicantly affect sound quality? If I situate the pre-amps and amplifiers near their speakers, but have the sources (DACs) far away so just the signal goes a long distance, is that OK?

(g) What is the terminology for the source signal versus power image? In other words, the way I understand it is that a DAC does not drive speakers, it just puts out a low-power analog signal. What is that signal called? Then the pre-amplifier takes that low power signal and input from an amplifier (?) and then outputs a power signal that goes to drive the speakers. What is that powered signal called?

As you can tell from my questions, I am trying to just orient myself and figure out how this stuff works and would greatly appreciate any guidance.