[SDR Listen to Audio Conversations?]

It looks like regular aircraft us frequency 117.975 to 137 mhz using AM, you will probably need a longer antenna then the rtl-sdr default antenna but you should be able to hear them

[SDR Trackable?]

Even if a device can detect a radio reciever, I would think it would be very hard to make out a sdr tuned to 1090 mhz with all the other radio and TV Devices in your home for example television, wireless and cell phones, wifi, bluetooth, wireless keyboards and mice, am and fm radios, that would be amazing technology if it existed to do that, plus not sure what it would accomplish if the could, at least in the US its not illegal

[Modes?]

TO kinda explain

WFM is for broadcast FM

NFM is for other FM broadcast like Police and HAM

AM is for as far the dongles go Aircraft I believe between 108 and 136

LSB/USB is for lower frequencies below 25 MHZ mostly HAm Radio you should here to much or none at all

DSB Not sure

CW again is for morse code for ham and you wont find much above 25 MHZ

RAW Not sure

Most broadcast will be NFM except aircraft and Broadcast FM

[I'm gonna get GNURadio-Companion working if it kills me!]

I had that problem I believe the version on depository for ubuntu is missing stuff usable for RTL-SDR, I did get it to work by some other install, search for GNU Radio and ubuntu and you will probably find the instructions. I will look for the install list I found for ubuntu 12.04 and will post when I find it ( I hope)

[Antenna that comes with the Realtek RTL2832U SDR]

Well ADB-S being 1090MHz is quite line of sightish so unless you can see the runway you won't see the planes on the ground.

With Mode-S and ADS-B planes leave it on all the way to the gate and turn it back on when starting up and leaving the gate. ADS-B and Mode-S MLat is used to track planes on the ground. This is particularly important at Airports which have zero visibility ILS systems as don't want planes crashing into each other. Also at these airports all the ground vehicles that leave the apron and go on taxiways and such are also tracked. For example on Flight Radar look at NZAA and you will usually some ground vehicles in addition to planes.

Thanks that's good info, the Denver airport is 20 Miles NE of of me and probably 300 ft lower along with all the buildings etc probably does limit reception

[Antenna that comes with the Realtek RTL2832U SDR]

MY reception, with the stock antenna inside ranges from 40 to 120 mile depending on direction. Interestingly All reception dies out at airports, I wonder if aircraft turn off the transmitter when going in for the approach for landing?

[Can not get SDR working/configured]

The blue light should turn on when plugged in and you should have a usb device in the device manager for bulk-in interface (interface 0). if that is there the drivers are probably good. you could try reinstalling the drivers

[adsb and height of antenna make a difference]

I watched the last show where they used a drone to raise the antenna 400' higher, kinda cool but will that really make a big difference when most aircraft will be above you and thus line of sight should not be an issue, For example where I am at in the Southern part of Denver, I see planes ranging from 7-8000 ft to 33000 ft elevation and I never see aircraft at DIA so they are either landing or taking off and to low, but I would think if I drove up Lookout mountain to receive, altitude wouldn't make a difference as long as I could see the airport and could then get the signals of the aircraft landing. Also from my experience it seems that the range airplanes broadcast seems to be limited to around 50 to 100 miles although I am using the antenna that came with the RTL usb Tuner and it sits on a metal base of a lamp and I would guess a well tuned antenna would do better. Interestingly I get better reception to the West over the mountains(80-90 Miles) then to the east (60 miles)