My $0.02, for what they're worth:
The photos are ok. The compositions don't grab me, and the light is flat and dull. But technically, they are fine. I think most people start out with shots like this when they first get a new DSLR (I know I did).
The old saying goes something like this: the beginner sees the subject, the experienced photographer sees the composition, and the master sees the light.
Put another way: it's ALL about the light. The next time you see a photograph you like, break the lighting down in your mind; where did the photographer place the shadows? How is light being used to emphasize (or deemphasize) different parts of the composition?
I also recommend 'Understanding Exposure' by Bryan Peterson; fantastic read and immensely valuable.
Re: the DoF conversation, keep in mind that most lenses are not at their best when used wide open. So, even if you were to purchase a 50/1.8, you will get much better results from that lens by stopping it down to f/2.8. Sharpness and contrast are markedly better, at the expense of a small increase in DoF (which may not be a bad thing) and a bit slower shutter speed.
For a 1.6x crop camera, consider the 35 f/2.0, which is far more useful than the 50 f/1.8.