UX1 and UX2 are essentially the same thing just the UX1 has half the inputs. So if you are recording solo and don't plan on recording in stereo with 2 mics then UX1 is more than enough.
I understand it sucks having to drop more money on hardware when you thought you had everything you need. It might be possible to get stuff to work with what you have... I'm not 100% sure. If you did manage to get what you have to work, the latency is probably going to be horrible. What I mean by that is the time you hit a note there will be probably about a half second delay before you hear it through the monitors. Getting an audio interface with ASIO drivers (such as UX1 or UX2 but there are many more) will eliminate that latency. Some people don't mind recording with that latency but I just can't handle it.
I haven't used Abelton Live that came with it, without looking at it I can almost guarantee you have a better program with GTP4. I forget the track limit on GTP4 (I upgraded to Sonar eventually) but it is higher than 8 tracks. If you are a guitarist then you'll really like POD Farm. Basically it does the same thing as Guitar Rig does that came with GTP4 but you'll have more options with the UX since GTP4 came with a LE edition of Guitar Rig. I also like the layout of Pod Farm better as the effects and everything is laid out like a pedal chain. It is easier for my brain to follow that. Personally I think the Pod Farm bundle makes the price worth it alone, I use it all the time. Some people like other stuff better but it has always fit my needs nicely.
Since you are just jumping into this, I'll let you in on some nice plugins that you can get for free as well. There is a thread around here somewhere with a big list, but go to Native Instrument's website. There you can download a bunch of free plugins from their virtual instruments collections Kore 2, Kontakt, etc. They literally have about 100 different products and these free packs are some sounds taken from each one. There are no restrictions on the free packs and I think I had fun with those for about 6 months before I went ahead and bought a couple of their products.
I hope all this helps. I think if you bought an external audio interface your recording experience will be much better and you'll be able to concentrate more on recording rather than fighting with your machine.