["Low" FM channels.]

The RTL-SDR is crazy good for the price but there are some things about it that just aren't that good. I would suggest searching for calibrating a rtl-sdr. The weather channels are typically pretty good at being on frequency and if you know what it is transmitting at you offset your sdr to match that frequency. The other problem is that these things have poor filtering and shielding. You may be seeing two signals (internal of the sdr mixed with external signal maybe) and end up with a signal showing up on your screen that is out of place and in reality not at that frequency. This could explain a FM station down that low. Also if you are near the Broadcast transmitter it could also just be spurious transmissions from the radio station that you are picking up because you are so close.

It would make sense to calibrate, however as I pointed out, all other channels are exactly where they should claim to be broadcasting. If I were to calibrate based on the weather channel assuming it was in fact broadcasting at the frequency it should, would then suggest that all other stations were in fact broadcasting off their frequency by that much. It seems more reasonable that the weather stations might be off, than that every station except the weather station is on a wrong frequency.

[Watching Planes on Windows]

I think I can answer my own question - I get a bunch of planes with NO Lat/Long data ... only planes with Lat/Long data actually display. So my question is - why wouldn't these other planes be broadcasting Lat/Long ?

I noticed this as well. I'm thinking that perhaps the planes are sitting on the edge of the range for the stock antenna. If this were the case, then adsb# may only be decoding what it can, which is why you get some planes with no data beyond the ICA024 and Registration, while others you might get the altitude or heading, etc. The signal may be too weak, or there may be too much interference for the receiver to pick up the full packet of information.

["Low" FM channels.]

It may be that the frequency tuning on the device may not be exact.

An option to be considered, but currently I have only found it at the weather stations, on my dongle (from the hakshop) all other stations are broadcasting exactly where expected.

[SDR on your phone.]

Works on the Nexus 5. Very nice piece of software.

["Low" FM channels.]

I did hear the call letters of the station broadcasting in the 49MHz range, it's actually a local FM radio station that lives at 102.5FM, Wow Country. Why it's also down at 49MHz is a really puzzle. I've also found out NOAA weather station, it's over at 162.393.000 even though they say they're broadcasting at 162.400.000.

I was also listening to a couple guys talk smack to each other yesterday in the 27MHz CB range, it was a hoot, LOL

I got my dongle today, after reading around I decided to look for the local weather station it broadcasts around 162.418 here even though it claims to broadcast on 162.425. This makes me wonder if all weather stations broadcast 7kHz below what they claim.