If you haven't received any answers to your questions yet, you can contact Liveatc directly about setting up a feed by going here:
http://www.liveatc.net/contactI can answer some of the questions...
3) Basic hardware requirements: air band antenna, coax cable (antenna to scanner radio), scanner radio, sound card preferably with Line In jack (I use Griffin iMics on my Pi setups), audio cable to connect scanner radio to sound device and lastly a programmed SD card for the Pi (provided by Liveatc).
4) While I am not an antenna expert, if you are only 3 miles from that municipal airport, the antenna in the attic idea should work quite well.
5) You mentioned setting up a feed for the municipal airport...it would be interesting to know if you can receive any other ground-side ATC transmissions like those from Fort Worth Center. Something like that would also make for an interesting feed.
Hope this helps...
Ron