The old PC must have at least 1GB of RAM and that was the only spec I had to deal with. I scrounged up some more RAM and then I was ready to go. Download the vortexbox iso from here : LINK
Then once you have it downloaded burn it to CD. I use Windows burn image to disk but if you are using an old version of windows just do a quick search and there are several free pieces of software.
Insert the disk and let if fly. Once it is done it will give you an ip address and you use the Web GUI for most of your configuration.
Once done I found it on my network and transferred all my Flac files to the correct directory.
I am using a variety of USB DAC's. For my critical listening I have a HRT music streamer to my theater zone. For the other zones I am using one of the recommended DAC's they sell from Small green computers (15 bucks + shipping) and a couple of Turtle beach Amigo II's.
Once the DAC's are connected they will show up in the vortexbox hardware list. You then configure each vortex player in the web gui to go to which USB DAC.
The in the Web GUI go to Logictech Music Server and view your players and finish configuring them. You will create an account at mysqueezbox.com to add your apps to your players.
To control from your mobile devices download the logictech squeeze play for free or I use OrangeSqeeze which I think has a better user interface for $2.99.
The analog outputs from these DAC's go to:
Music streamer (theater zone)-> AV7005 prepro -> using prepro volume control for bitperfect playback
Noname DAC (garage) -> Speakercraft BB50 -> using player volume control to amp. Not as high quality sound but with in ceiling speakers it is not as critical
Amigo DAC (house zones)-> Onkyo amp -> player volume control.
Amigo DAC (outdoor zone) - Onkyo amp -> player voume control
I think that gets to all of your questions. There are some other tweaks that I did during this process that are listed on the vortexbox wiki (setting static IP, freezing DAC hardware list) but those can be done later.