Hi guys. I’ve read thru the introduction to recording (thanks for that) and other posts, and still have a couple of questions. I just want to record for my own development. My priorities are keeping the price down, avoiding buying unnecessary hardware, and recording with a backing track existing on my PC.

If I use a cheap USB link like the Behringer, can I record with a backing track using software like the free version of Guitar Rig? Can I monitor the session using my PC speakers? 

yes you can and yes you can.  You'll need to plug your speakers into the behringer guitar link thing.

However, there is a huge difference in quality between the cheapest usb interface and the next step up.  Is there any way you can save an extra 100$ or 200$?
Guitar Rig is more of a modeling software, if you want to record you'll need a DAW, something like Mixcraft, Reaper, Tracktion, etc...

Once you've installed the DAW software you can load guitar modelers as vst plugins inside it and change your amp, etc.

Good starter pack would be something by PreSonus or one of the other manufacturers, as these usually come with the interface as well as the software to get started.