I wouldn't call myself an experienced singer by any means (been at it seriously for a couple of years now), but I'll try.
Your pitch is actually quite good for a lot of people I've heard. I think other parts of your singing need work though. From your tone you sound to me like a natural tenor. Those high notes shouldn't be giving you much trouble at all. If they feel uncomfortable it probably means you have a problem with proper breathing.
I think your voice sounds a bit more nasally than it should. You're going to have to open up your voice by using deep breathing techniques as you sing. I'm not sure if you've really practiced breathing for singing; it's very similar to how you breath when you sleep. When you yawn is the perfect time to go for a really high note on the exhale (just try singing opera and see what happens). Anyway, as a practical exercise, keep your shoulders down while you sing; force them to stay down if you have to. We tend to breath from a higher position and force the notes to come out rather than give them the support they really need, which only comes from deep natural breathing. Always stand up while you sing while maintaining good posture. A good singing posture allows a natural flow of air.
Anyway, I liked the first version (the higher one) much better than the second version. You seemed to have much more energy, although I'm sure it probably felt uncomfortable for you. I remember when I first started I would feel very uncomfortable going past a C or D. Now I can sing almost a full octave higher using my full voice (although it takes me tons of energy to hit that Pavorotti high C since I'm a natural baritone).
Once you master deep breathing then it becomes much easier to have complete control over your voice and add emotion. Once you get to the final stages of mastering a song, you need to sing the meaning of the words, rather than try to hit the notes. Only then have you truly mastered it. It sounded too much to me like you were just singing words and not really singing what they mean.
Now as for the actual song, I would recommend singing the introduction in a lower voice (like you did for version 2), then moving it up a full octave higher for the energetic part. Of course it's going to take a lot of practice working on your range, but from what I heard I think you have the talent to make it work. Just keep practicing and especially work on your breathing to get the maximum breath support possible to sustain the high notes (the higher the pitch you sing, the more breath it takes to sustain the note).
As for the guitar part, I'm not crazy about the guitar part in the beginning of the song (although I'm a pianist, so you don't have to take my word for it). I'd recommend some slower strumming or arpeggios to make it more interesting. It would make the song feel more emotional in my opinion. I enjoyed the faster part of the guitar playing, however, so just keep it up what it is you do. Drums and bass and backup vocals may not be necessary; there are plenty of good acoustic songs out there also. At least worry about mastering an acoustic version first.
As for Audacity, it's a decent program for recording (at least as far as free software goes), but really not ideal for mixing and mastering. If it's all you have the budget for, fine, but you may eventually want to invest in some better software. I've used FL Studio for years (since 3.0) and it hasn't let me down (and it's a steal at under $100), although you may have to learn some really advanced mixing techniques if you want to produce quality music using the software. However, it's hard to find a better deal on a complete software package.