My go at answering these!!
1. I need the Raspberri Pi 3 module - which includes the wifi module. Correct (Someone on facebook was selling completed ones for around $240 last year, where I got mine)
2. I need a 1090 Mhz receiver and antenna suitable for aircraft (not one of the ground based monsters) Correct
3. I need a stable 5V (USB) power supply Correct , you can use a powerpack, in my aircraft I use the 12v power supply from the aux power (Cigarette lighter power)
4. I don't need a GPS module as the iPad GPS knows my position. Correct, assuming you have the 3G version, just a wifi version does not have the GPS chip.
5. I need to install some software on the raspberry pi. (not sure what talks best with ozrunways??) Correct, quire a few sites out there detailing how to do this. Or you buy one like I did
6.There is no point having the the dual band as Air Services don't intend to put in transmitters for the ground the based 978Mhz Correct
7. I will not get ADS-B weather as Air Services don't intend to put in transmitters for weather. Correct
8 I cannot provide an ADS-B out to other aircraft location without a "real" transponder-squitter ($$+) [but is not required for VFR /class G/ RAA anyway] Correct, who knows what will come in future with low cost ADSB out solutions
9. Oz runways will show Ozrunways traffic via the 3g iPad data as usual. Correct and ADSB, I pick up the Jets going overhead, interesting to see how fast they move!! Also picked up a few helicopters nearby too.
10. ADS-B traffic will appear in ozrunways (similar to native ozrunwas traffic?) via Wifi from the Raspberry Pi. Correct
11. ADS-B traffic is (IFR, some GA VFR and new aircraft after 2014) Anyone that has ADSB out fitted and it is turned on. Seen a RAAus aircraft with it too!! And ADSB is mot mandated for RAAus VFR, so may only have mode S
12. non ADS-B Avplan traffic will not be visible Correct
13. non ADS-B map and compass traffic will not be viable. Correct
14. non ADS-B glider traffic will not be visible (Some vintage also) Correct , alot of gliders have flarms. Depending how old their flarm is, they may see you if you have Mode C / S or ADSB.
If you have more questions, keep asking, and start googling. If you are interested in who was building and selling them, let me know and I will see if I can dig it up.